Image display device and light emission device

ABSTRACT

An image display device including a light emission section which emits light to an intensity adjusting section and a wavelength conversion section which change the intensity and wavelength of the emitted light. Phosphors and phosphor like materials are employed in wavelength conversion and a liquid crystal is employed for the light adjustment. The light emission device may include plural semiconductor light emitting elements having a different wavelength ranges such as diodes stacked in a compact and predetermined order such that wavelengths of light from each diode are emitted from the light emitting elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityunder 35 USC §120 from U.S. Ser. No. 11/504,682, filed Aug. 16, 2006,which is a continuation application of U.S. Pat. No. 7,110,061, issuedon Sep. 19, 2006, which is a divisional application of Ser. No.10/956,136, filed Oct. 4, 2004, which is continuation application ofU.S. Pat. No. 6,864,627, issued Mar. 8, 2005, which is divisionalapplication of U.S. Pat. No. 6,586,874, issued Jul. 1, 2003, and claimsthe benefit of priority under 35 U.S.C. §119 from Japanese PatentApplication No. 127426/1997, filed May 16, 1997, the entire contents ofeach of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an image display device and a lightemission device, more particularly to an image display device of a smallsize with high performance and high reliability and a light emissiondevice which is suitable for various kinds of uses including a lightsource of the image display device.

An image display device plays a role as an interface that visuallyconnect various kinds of electrical equipment and human beings. In thepresent information society, the role of image display devices isessential, and the image display device is a key component in a widefield that includes television sets, computers, information terminals,game machines and household electronic appliances. At the same time,development of new high performance image display devices is desired tomeet the needs of the present information society as it rapidly developsand increases in diversity.

For such image displaying devices, a Braun tube and a liquid crystaldisplay device have been mainly used. The Braun tube scans an electronbeam in a glass tube sealed to produce a vacuum and excites fluorescentbodies arranged on a shadow mask, thereby displaying an image. The Brauntube can be manufactured relatively low in cost, and is capable ofdisplaying high quality images. Therefore, in general, the Braun tube iswidely used as an image display device for television sets, computermonitors, etc.

On the other hand, a liquid crystal display device applies a designatedelectric field to a liquid crystal layer held between two substrates,thereby changing an optical property of the liquid crystal layer todisplay changes of intensities of transmitted light and reflected lightin the form of a predetermined image. When the liquid crystal displaydevice is compared with the Braun tube, the liquid crystal displaydevice has an advantage that it is thin in thickness and light inweight. Liquid crystal display devices are used in electronic equipmentsuch as notebook computers and various kinds of portable informationconsole units.

With the development of the foregoing electronic equipment and theadvancement of the information society, image display devices must bemade smaller in size, lighter in weight, and display an image withhigher quality and reliability.

However, the Braun tube has structural problems because it is large inlength in its tube direction, heavy in weight, and since it is a vacuumglass tube, it has an insufficient durability against vibrations andshocks.

On the other hand, a conventional liquid crystal display device uses acathode fluorescent tube as its light source, which meets manufacturersneeds for a small-sized, thin cathode fluorescent tube having long life,in addition to having display luminance. However, there is a problem inliquid crystal display devices, that the visual field angle is narrowerthan that of the Braun tube, so that image recognition from an obliquedirection is significantly poor.

The present invention was made from the viewpoint of the above describedcircumstances. Specifically, the object of the present invention is toprovide an image display device which is easy to manufacture, small insize, light in weight, having has a wide visual filed angle, capable ofdisplaying a high quality image, and having a high reliability, and toprovide a light emission device which is suitably used for a lightsource of such image display device and for other various kinds of uses.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a novelimage display device that comprises a light source section whichincludes a semiconductor light emitting element as a light source, alight adjustment section which adjusts an intensity of a light emittedfrom the light source section for each of pixels, and transmits thepixels as a transmission light. The image display device also includes awavelength change section which receives the transmission lighttransmitted from the light adjustment section and emits light having anintensity spectrum different from that of the transmission light.

The light adjustment section in the image display device adjusts theintensity of the transmission light by a liquid crystal cell, and thewavelength change section comprises a phosphor.

The semiconductor light emitting element of the light source section isthe one which emits a light exhibiting a light emission spectrum havinga peak wavelength in a ultraviolet region. The wavelength change sectioncomprises three kinds of phosphors arranged according to a predeterminedpixel pattern. The three kinds of the phosphors are the ones whichconvert the said transmission light into visible rays of lights of red,green and blue wavelength zones, respectively, whereby the image displaydevice can display a clear and bright image with a low powerconsumption.

Moreover, the semiconductor light emitting element comprises a galliumnitride type semiconductor as a light emitting layer, in which a peakwavelength of a light emission spectrum is set to be at a range of 360nanometer to 380 nanometer. The wavelength change section uses aphosphor exhibiting an absorption excitation peak in a wavelength regionwhich is substantially the same as that of the said peak wavelength ofthe foregoing phosphors, whereby an image display device of a highefficiency can be provided.

Moreover, a light transmitting substrate of the light adjustment sectionis formed of a low alkali glass, a no-alkali glass or a quartz glass,whereby the absorption of a ultra violet ray is reduced so that aluminance is increased.

Moreover, by providing an ultra violet absorption filter in thewavelength change section, it is possible to suppress the entry of aultra violet ray from the outside as well as the leakage of a ultraviolet ray emitted from the semiconductor light emitting element to theoutside.

Moreover, the semiconductor light emitting element exhibits a lightemission spectrum, in which the peak wavelength is at a blue range. Thewavelength conversion section comprises two kinds of phosphors and onekind of filters, arranged according to a predetermined pixel pattern.The two kinds of phosphors are organic phosphors which convert theforegoing transmission light to a visual light in a wavelength zone suchas red or green zone and one kind of filter transmit the foregoingtransmission light, so that the image display device with a highefficiency can be provided.

On the other hand, the image display of the present invention may bealternatively constituted in such a manner that a light source sectionincluding a semiconductor light emitting element as a light source, awavelength change section which receives light emitted from thesemiconductor light emitting element and emits a light exhibiting adifferent intensity spectrum from that of the received light, and alight adjustment section which adjusts the intensity of the lightemitted from said wavelength change section, corresponding to each pixelof an image to be displayed, and transmits it as a transmission light.

Moreover, the semiconductor light emitting element as the light sourceof the image display device emits a light exhibiting a light emissionspectrum, a peak wavelength of which is in an ultraviolet ray range, andthe phosphors convert the lights emitted from the said light conductionplate to visible lights having respective peaks in wavelengths zones ofred, green and blue thereof.

Moreover, the light adjustment section comprises either a guest-hosttype liquid crystal or a high polymer diversion type liquid crystal. Tokeep balance of luminance for every color, the pixel pattern hasdifferent pixel area depending on each color, and the light sourcesections may be constructed in various types, whereby it will make itpossible to display a clear image with a high efficiency.

Moreover, the image display device of the present invention comprises alight source section having a semiconductor light emitting element and amovable reflection mirror in the light source section, and a wavelengthchange section which receives a light emitted from said light sourcesection to emit it after changing its intensity spectrum, wherein thelight from the semiconductor light emitting element is reflected bymoving the movable reflection mirror and the reflected light is incidentonto a predetermined position of said wavelength change section.

Moreover, the image display device of the present invention may comprisea variable lens instead of the movable reflection mirror.

On the other hand, the light emitting element of the present inventioncomprises a light emitting diode which includes a gallium nitride typecompound semiconductor as a light emitting layer and a phosphor which isdeposited in at least one portion of a surface of the light emittingdiode, wherein the light emitted from the light emitting diode issubjected to a wavelength change by said phosphor and is emitted to anoutside of the light emitting diode.

Moreover, the light emitting element of the present invention comprisesa mounting material, the light emitting diode which includes a galliumnitride type compound semiconductor as a light emitting layer mounted onthe mounting material, and resin molding the light emitting diode,wherein a phosphor is deposited on a surface of the resin and the lightemitted from the light emitting diode is subjected to a wavelengthchange by the phosphor and is emitted to the outside.

Alternatively, the light emitting element of the present inventioncomprises a mounting member, the light emitting diode mounted on themounting member, and resin which molds the light emitting diode, whereinsaid mounting member comprises a reflection plate provided around themounting member of the light emitting diode and a phosphor deposited ona surface of the reflection plate, and wherein a light emitted from thelight emitting diode is subjected to a wavelength change by the phosphorand is emitted to the outside.

Alternatively, the light emitting element of the present inventioncomprises a light transmission substrate, a layer formed of a phosphorstacked on the light transmission substrate, and a light emitting diodewhich includes a gallium nitride type compound semiconductor as a lightemitting layer, being mounted on the phosphor layer, wherein a lightemitted from the light emitting diode is subjected to a wavelengthchange by the phosphor layer, and is emitted to the outside aftertransmitting through the light transmission substrate.

Or, the light emitting element of the present invention comprises alight emitting diode having a multi-layered structure composed of aplurality of semiconductor layers including at least one gallium nitridetype compound semiconductor, wherein at least one of said semiconductorlayers includes a phosphor which performs a wavelength change for alight emitted from said light emitting diode and emits it to theoutside.

Or, the light emitting element of the present invention comprises aplurality of light emitting diodes, each of which emits a light of awavelength different from those emitted from other light emitting diodesand is stacked so as not to shade the light emitted from other diodeswhen viewed from a light exiting direction, wherein the light emittedfrom each of the light emitting diodes can be taken from the lightexiting direction.

According to the present invention, it is possible to provide an imagedisplay device which is capable of displaying an image with a very widevisual field angle compared to an ordinary liquid crystal displaydevice, the image being recognized clearly even when viewed obliquely.

According to the present invention, it is possible to provide an imagedisplay device which is capable of displaying a distinctive imagewithout blur and vagueness.

According to the present invention, since in the image display device ofthe present invention the light source section employs the semiconductorlight emitting element as a light source, the image display device canexhibit an extremely high photoelectric conversion efficiency and has anability to reduce power consumption compared to the conventional imagedisplay device such as the liquid crystal display device.

According to the present invention, the image display device of thepresent invention employs the semiconductor light emitting element as alight source, whereby a high photoelectric conversion efficiency can beachieved and the power consumption can be reduced compared to theconventional cathode fluorescent tube. For example, the powerconsumption of a 10.4 inch type thin film transistor (TFT) liquidcrystal display device using the conventional cathode fluorescent tubeas a light source is about 9 watts. On the contrary, the powerconsumption of the image display device adopting an ultra violet LED andthe phosphor is about 4 watts, specifically, the power consumption isreduced to be less than half of that of the conventional liquid crystaldisplay device. As a result, battery life of portable electronicequipment such as a notebook type computer and various kinds ofinformation portable console units which incorporate the image displaydevice of the present invention can be prolonged.

Moreover, according to the present invention, in the light sourcesection of the image display device, the circuit thereof is simplifiedcompared to the conventional cathode fluorescent tube, where the drivingvoltage for the light source section can be reduced. Specifically, theconventional cathode fluorescent tube had to be applied with a highvoltage via a stabilizing circuit or an inverter. However, according tothe present invention, the semiconductor light emitting element servingas a light source has an ability to provide a sufficient light emissionintensity with a DC voltage as low as 2 to 3.5 volts. Therefore, thereis no need of a stabilizing circuit or an inverter circuit for thesemiconductor light emitting element, so that the driving circuit forthe light source is greatly simplified and the driving voltage fordriving the light source can be reduced.

Moreover, according to the present invention, the life time of the lightsource incorporated in the image display device can be significantlyprolonged than that of the conventional image display device.Specifically, in a conventional cathode fluorescent tube, luminance israpidly lowered after the passage of a predetermined life time perioddue to sputtering phenomenon at the light source section, and lightemission stops. According to the present invention, reduced luminance israrely found even when the light source has been used for an extremelylong time as long as several tens of thousands of hours, and the lifetime of the light source can be said to be quasi-permanent.

Moreover, the image display device of the present invention has a veryshort rise-up time for the light emission. Specifically, the period oftime from a signal input for starting of driving to a stationary statein the light emission is very short compared to the conventional cathodefluorescent tube so that the image display device of the presentinvention is capable of starting an operation instantaneously.

According to the present invention, the reliability of the image displaydevice of the present invention can be increased. Specifically, theconventional cathode fluorescent tube has a structure that seals aspecified gas in a glass tube. Therefore, in some cases, the cathodefluorescent tube is broken by excessive shock and vibration. Accordingto the present invention, however, since the semiconductor lightemitting element that is a solid state element is used as a lightsource, reliability against shock and vibration increases remarkably.

Moreover, according to the present invention, there is no need ofharmful mercury. Specifically, in the conventional cathode fluorescenttube, a designated amount of mercury is often sealed in its glass tube.The image display device of the present invention need not use suchharmful mercury.

Moreover, the light emitting element of the present invention is smallin size, thin in thickness, and exhibits high luminance and is reliable.A plurality of emitted lights having different wavelengths such as red,green and blue colors can be simultaneously produced from the lightemitting element of the present invention. As described above, accordingto the present invention, provided are the image display device and thelight emitting element which have simple constitutions and are small insize with a high reliability. In addition, excellent industrialadvantages, including those described above and hereinafter, can bebrought about by the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is an illustration of a sectional view showing an outline of aconstitution of an image display device according to a first embodimentof the present invention;

FIG. 2 is an illustration of sectional view of an image display device10 a according to the present invention;

FIG. 3 is an illustration of a sectional view showing an outline of adetailed constitution of another image display device 10 b according tothe present invention;

FIG. 4 is a chart illustrating concrete examples of semiconductor lightemitting elements suitably used for a light source section of the imagedisplay devices according to the present invention;

FIG. 5 is a graph of light emission efficiency versus wavelength for aphosphor which is suitably used for a wavelength change section 40 b ofthe image display device 10 b shown in FIG. 3;

FIG. 6 is an illustration of is a sectional view of an image displaydevice 10 c shown in FIG. 3;

FIG. 7 is an illustration of a sectional view of an image display device10 d shown in FIG. 3;

FIG. 8 is a sectional view showing an outline of still another concreteconstitutional example of the image display device 10 a shown in FIG. 3;

FIG. 9 is a sectional view showing an outline of further still anotherconcrete constitutional example of the image display device 10 a shownin FIG. 3;

FIG. 10 is a sectional view showing an outline of further still anotherconcrete constitutional example of the image display device 10 a shownin FIG. 3;

FIG. 11 is a sectional view showing an outline of further still anotherconcrete constitutional example of the image display device 10 a shownin FIG. 3;

FIG. 12 is a sectional view showing an outline of further still anotherconcrete constitutional example of the image display device 10 a shownin FIG. 3;

FIG. 13 is a sectional view showing an outline of a constitution of animage display device according to a second embodiment of the presentinvention;

FIG. 14 is a sectional view showing an outline of a constitutionalexample of an image display device 50 of the present invention;

FIG. 15 is a sectional view showing an outline of a constitution of amodification example of an image display device 50 a of the presentinvention;

FIG. 16 is a sectional view showing an outline of a constitution of amodification example of an image display device 50 of the presentinvention;

FIG. 17 is a sectional view exemplifying a constitution of atransmission type image display device which uses a light adjustmentsection 30 k capable of being used in the present invention;

FIG. 18 is a constitutional view exemplifying an outline of a reflectiontype image display device which uses a light adjustment section 30 k;

FIG. 19 is an explanatory view showing an example in which an area ofeach pixel is optimized in the image display device of the presentinvention;

FIG. 20 is a constitutional view showing an outline of a concreteexample of the light source section 20 of the image display device 10 or50 according to the present invention;

FIG. 21 is a constitutional view showing an outline of a second concreteexample of the light source section of the image display sectionaccording to the present invention;

FIG. 22 is a constitutional view showing a third concrete example of thelight source of the image display device according to the presentinvention;

FIG. 23 is a constitutional view showing a fourth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 24 is a constitutional view showing a fifth concrete example of thelight source of the image display device according to the presentinvention;

FIG. 25 is a constitutional view showing a sixth concrete example of thelight source of the image display device according to the presentinvention;

FIG. 26 is a constitutional view showing a seventh concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 27 is a constitutional view showing an eighth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 28 is a constitutional view showing a ninth concrete example of thelight source of the image display device according to the presentinvention;

FIG. 29 is a constitutional view showing a tenth concrete example of thelight source of the image display device according to the presentinvention;

FIG. 30 is a constitutional view showing an eleventh concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 31 is a constitutional view showing a twelfth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 32 is a constitutional view showing a thirteenth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 33 is a constitutional view showing a fourteenth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 34 is a constitutional view showing a fifteenth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 35 is a constitutional view showing a sixteenth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 36 is a constitutional view showing a seventeenth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 37 is a constitutional view showing a eighteenth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 38 is a constitutional view showing a nineteenth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 39 is a constitutional view showing a twentieth concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 40 is a constitutional view showing a twenty-first concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 41 is a constitutional view showing a twenty-second concreteexample of the light source of the image display device according to thepresent invention;

FIG. 42 is a constitutional view showing a twenty-third concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 43 is a constitutional view showing a twenty-fourth concreteexample of the light source of the image display device according to thepresent invention;

FIG. 44 is a constitutional view showing a twenty-fifth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 45 is a constitutional view showing a twenty-sixth concrete exampleof the light source of the image display device according to the presentinvention;

FIG. 46 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 47 is a sectional view showing an outline of a concrete example ofthe light source section 22A;

FIG. 48 is a sectional view showing an outline of a concrete example ofthe light source section 22A;

FIG. 49 is a sectional view showing an outline of a concrete example ofthe light source section 22A;

FIG. 50 is a sectional view showing an outline of a conventional lightsource, which is illustrated for comparison with the present invention;

FIG. 51 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 52 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 53 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 54 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 55 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 56 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 57 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 58 is a sectional view showing an outline of a concrete example ofthe light source 22A;

FIG. 59 a sectional view showing an outline of a concrete example of thelight source 22A;

FIG. 60 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 61 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 62 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 63 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention;

FIG. 64 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention; and

FIG. 65 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly to FIG. 1, thereof, the present invention provides an imagedisplay device which is capable of displaying a high quality image witha wide visual field angle and a low power consumption, by combining invarious forms a material having a wavelength conversion function, alight adjustment mechanism for adjusting an intensity of a transmissionlight and a semiconductor light emitting element. Moreover, the presentinvention provides a small-sized light emission device which emits aplurality of lights with high luminance, each of the lights having adifferent wavelength.

In FIG. 1, there is provided a sectional view showing an outline of aconstitution of an image display device according to a first embodimentof the present invention. Specifically, the image display device 10 ofthe present invention comprises a light source section 20, a lightadjustment section 30, and a wavelength conversion section 40. Or, theimage display device 10 may comprise a wavelength selection section 40instead of the wavelength conversion section 40. The light sourcesection 20 includes semiconductor light emitting elements appropriatelyarranged therein, and emit light incident onto the light adjustmentsection 30. The light has predetermined wavelength and quantity oflights, and exhibits a predetermined luminance distribution.

The light adjustment section 30 adjusts the light incident from thelight source section 20 thereinto every pixel, and transmits theadjusted light through the wavelength conversion section 40, whichappropriately changes the wavelength of the light incident from thelight adjustment section 30, and emits the light outside of the imagedisplay device 10.

According to the present invention, a spatial intensity distribution ofthe light emitted from the wavelength conversion section or thewavelength selection section 40 can be approximated to an intensitydistribution displayed by an aggregate of point light sources formed bythe wavelength conversion section 40 as the light source. Therefore,there is an extremely wide angle of visual field compared to ordinaryliquid crystal display devices, and the image display device of thepresent invention is capable of displaying an image clearly recognizedeven when it is observed from an oblique angle.

According to the present invention, the light emitted from thewavelength conversion section 40 is directly output without passingthrough the light adjustment section 30. The wavelength of the lightbeing changed by the wavelength conversion section 40 is disposed in thefront plane of the image display device 10. Therefore, no blur orvignette are produced, and a distinct image can be obtained.

According to the present invention, the light source section 20 employsthe semiconductor light emitting element as a light source, resulting ina high photoelectric conversion efficiency and reduction in powerconsumption compared to conventional image display devices such asliquid crystal display devices.

FIG. 2 is a sectional view showing an outline of the concrete structureof the image display device of the present invention. Specifically, theimage display device 10 a shown in FIG. 2 comprises a light sourcesection 20, a light adjustment section 30 a and a wavelength changesection 40 a.

The light source section 20 comprises a semiconductor light emittingelement as a light source, which posses a designated light emissionspectrum.

The light adjustment section 30 a has a structure that adjusts thetransmission ratio of a light with liquid crystal. Specifically, in thelight adjustment section 30 a, liquid crystal layer 36 is held betweenpolarizing plates 31 and 39. By applying a designated voltage betweenpixel electrodes 34 and the opposite electrode 38, the orientation stateof molecules in the liquid crystal layer 36 is controlled and the liquidcrystal layer 36 acts with the upper and lower polarization plates 31and 39, whereby the transmission ratio of the light can be controlled.Each pixel electrode 34 is supplied with a designated voltage viaswitching elements 35. For switching elements 35, a metal-insulatinglayer-metal (MIM) coupling type element or a thin film transistor (TFT)formed from a hydrogenized amorphous silicon or polycrystalline siliconcan be used, for example.

The wavelength conversion section 40 a has a structure which phosphors44 are disposed on the lower surface of transparent substrate 42.Phosphors 44 may be arranged so that the pixels are partitioned fromeach other by black matrixes formed of a light shading material. Or, thephosphors 44 may be arranged on the upper surface of the transparentsubstrate 42.

In an image display device such as image display device 10 a, the lightadjustment section 30 a adjusts the amount of light of every pixelemitted from the light source section 20, depending on the voltageapplied to the liquid crystal layer 36. Then, the light is incident ontothe phosphors 44. Then the wavelength of each pixel is converted atphosphors 44, thereby forming a designated image. Here, the phosphors 44may be a long wavelength conversion type phosphor, specifically, theymay be a phosphor that, upon receipt of an incident light, changes theincident light into a light having a longer wavelength and emits it. Or,the phosphors 44 may be a phosphor that changes the incident light intoone having a wavelength shorter than that of the incident light andemits it.

According to the present invention, since the semiconductor lightemitting element is used as a light source, the photoelectric conversionefficiency is higher than that of the conventional cathode fluorescenttube, and power consumption can be reduced. Moreover, in the newstructure the phosphor is excited by the light emitted from thesemiconductor light emitting element which has a high photoelectricconversion efficiency, resulting in reduced power consumption of theimage display device as a whole.

As one example, in the case of the 10.4 inch type TFT liquid crystaldisplay device using a conventional cathode fluorescent tube as a lightsource, the power consumption was about 9 watts. However, in case of theimage display device of the present invention, using a ultra violet rayLED and phosphors, the power consumption is about 4 watts, so that powerconsumption is reduced to less than half of that of the conventionalliquid crystal display device. As a result, the battery cells ofportable type electronic equipment such as notebook type computers andvarious kinds of portable information terminal equipment can beprolonged.

Moreover, the image display device of the present invention can achievea simplification of the circuit constitution and a reduction in thedriving voltage, compared to a conventional cathode fluorescent tube.Specifically, a conventional cathode fluorescent tube had to be appliedwith a high voltage via a stabilizing circuit or an inverter. However,according to the image display device of the present invention, thesemiconductor serving as the light source can produce a sufficient lightemission intensity with a DC voltage as low as 2 to 3.5 V. Therefore, astabilizing circuit or an inverter is unnecessary so that the drivingcircuit of the light source is greatly simplified and at the same timethe driving voltage is reduced.

Moreover, according to the image display of the present invention, thelife of the light source can be significantly prolonged. Specifically,the luminance of the emitted light declines rapidly in a conventionalcathode fluorescent tube and light emission stops after the expirationof a predetermined life time, due to a sputtering phenomenon at itselectrode section. However, according to the image display device of thepresent invention, the semiconductor light emitting element of the lightsource scarcely exhibits any drop of luminance of the emitted lightafter it has been used for a long time such as tens of thousands ofhours. It can be said that the life time of the semiconductor lightemitting element is quasi-permanent. Therefore, the image display deviceof the present invention has greatly prolonged life compared to aconventional device. Moreover, according to the present invention, theimage display device has an extremely short rise-up time to start anoperation. Specifically, the time from turning on of the power to asteady state of illumination luminance is very short compared to theconventional cathode fluorescent tube, so that the image display deviceof the present invention is capable of starting its display operationvirtually simultaneously.

According to the present invention, the image display device of thepresent invention has increased reliability. Specifically, theconventional cathode fluorescent tube has a structure that its glasstube is charged with specified gas. Therefore, the conventional cathodefluorescent tube may be broken due to excessive shock or vibration.However, according to the present invention, since a semiconductor lightemitting element which is a solid state element, is employed as thelight source, durability against shock and vibration increasesremarkably. As a result, the reliability of various kinds of portableelectronic equipment mounting the image display device of the presentinvention can be increased greatly.

Moreover, according to the present invention, harmful mercury is notused. Specifically, in a conventional cathode fluorescent tube, adesignated amount of mercury is often charged in its glass tube.However, according to the present invention, it is unnecessary to usesuch harmful mercury.

FIG. 3 is a sectional view showing an outline of a concrete structure ofimage display device 10 b of the present invention. Specifically, theimage display device 10 b shown in FIG. 3 comprises a light sourcesection 20, a light adjustment section 30 a and a wavelength conversionsection 40 b.

The light source section 20 comprises a semiconductor light emittingelement as a light source, which emits light in an ultraviolet rayrange. For example, gallium nitride which is explained in FIG. 4 shouldpreferably be used for a material forming a light emitting layermaterial of the light emitting element.

The wavelength conversion section 40 b includes phosphors 44 a, 44 b,and 44 c, arranged in a predetermined pattern. The phosphors convertlight wavelength ranges of light emitted from the light adjustmentsection 30 a into visible rays of red, green, and blue wavelength light,respectively.

FIG. 4 is an explanatory chart concerning a concrete example of asemiconductor light emitting element which is suitably used for thelight source of the image display device. In FIG. 4, wavelengths oflight, colors corresponding to each of the wavelengths and materials ofcompound semiconductors, each of which has a light emission peak in thecorresponding wavelength zones, is shown.

In the image display device 10 b shown in FIG. 3, the wavelength oflight from the light source 20 is changed and output by the conversionsection 40 b. Here, phosphor is a means for changing the wavelength, andthe wavelength conversion section 40 b performs in many cases what iscalled long wavelength conversion, which emits light having a longerwavelength than that of the incident light. Therefore, in order torealize a full color display, the wavelength of the semiconductor lightemitting element should be shorter than that of blue color which has theshortest in the visible light range. In addition, the semiconductorlight emitting element must also exhibit a high light emission luminanceat the same time.

For a material of such semiconductor light emitting element satisfyingthese requirements, gallium nitride can be utilized. A semiconductorlight emitting element that uses gallium nitride as a light emittinglayer, and emits light of a wavelength ranging from 360 to 380nanometer, has a high light emission efficiency. Therefore, using such asemiconductor light emitting element as a light source, an image displaydevice which displays a clear image with a high luminance can berealized.

The light adjustment section 30 a of the image display device 10 b shownin FIG. 3 can be constituted similar to that of the image display device10 a shown in FIG. 2. Accordingly, the same material parts in the lightadjustment section 30 a and the light adjustment section of imagedisplay device 10 a are denoted with the same reference numerals, anddescriptions for them are omitted.

Moreover, the wavelength change section 40 b of the image display device10 b has a constitution in which phosphors 44 a, 44 b and 44 c arearranged on the lower surface of the transparent substrate 42 so as toform a designated pattern. For the material of the phosphors 44 a, 44 band 44 c, the one that has an excitation characteristic that agrees withthe light emission characteristic of the light source of light sourcesection 20 should be preferably used.

FIG. 5 is an explanatory drawing concerning a concrete example of aphosphor suitable to be used in the wavelength conversion section 40 bof the image display device 10 b. Specifically, in FIG. 5, exemplifiedis a relation between a relative light emission efficiency of a phosphorand a wavelength of light incident thereto. The phosphor shown in FIG. 5exhibits the maximum light emission efficiency of the wavelength of theincident light, at the ranges from 340 to 380 nanometer. Specifically,the phosphor shown in FIG. 5 indicates an excitation peak in thewavelength zone of the light emitted from the light emitting elementwhich was explained in FIG. 4. By combining this phosphor with thesemiconductor light emitting element explained with FIG. 4, an extremelyhigh photoelectric conversion efficiency can be achieved. Moreover, thewavelength of the light emitted from the phosphor can be suitablyselected by introducing specified impurities thereinto. Thus, the imagedisplay device 10 b of the present invention will be capable ofincreasing luminance in an image display and displaying a bright andclear image.

For such phosphor, for example, a substance such as Y₂O₂S:Eu foremitting a red color will be mentioned; (Sr, Ca, Ba, Eu)₁₀(PO₄)₆Cl₂ foremitting a blue color; and 3(Ba, Mg, Eu, Mn)O.8Al₂O₃ for emitting agreen color.

By using such phosphor, the wavelength of the light in the ultravioletrange emitted from the light source section 20 can be converted withhigh efficiency. The phosphors 44 a, 44 b and 44 c receive the light inthe ultraviolet range from the light source section 20 to convert thewavelengths of the light, and output lights in red (R), green (G) andblue (B) wavelength ranges respectively, thereby forming the designatedcolor image.

Moreover, each pixel of phosphors 44 a, 44 b and 44 c may be partitionedby the black matrix formed of a light shading material. Or, they may bearranged on the upper surface of the transparent substrate 42. When theyare arranged on the upper surface of the transparent substrate 42, blursand vignettes of the image can be suppressed by interposing thetransparent substrate 42.

The image display device 10 b of the present invention exhibits thefollowing effects, in addition to those of the foregoing image displaydevice 10 a.

Specifically, the image display 10 b employs the semiconductor lightemitting element which emits light at the ultraviolet range as the lightsource, and at the same time employs a phosphor in the same ultravioletray range which exhibits a high photoelectric conversion efficiency,whereby the image display device 10 b can display an image with anextremely high display luminance.

FIG. 6 is a sectional view showing an outline of a concrete structure ofimage display device 10 c of the present invention. Specifically, theimage display device 10 c shown in FIG. 6 comprises a light sourcesection 20, a light adjustment section 30 b and a wavelength conversionsection 40 b.

The light source section 20 comprises a semiconductor light emittingelement which emits light at the ultraviolet ray range, similar to theforegoing image display device 10 b. Gallium nitride which was describedabove should be preferably used for a material of a light emitting layerof the semiconductor light emitting element.

The light adjustment section 30 b has a constitution in which a lighttransmission ratio is adjusted by liquid crystal, similar to theforegoing image display device 10 b. Specifically, in the lightadjustment section 30 b, a liquid crystal layer 36 is held betweenpolarization plates 31 and 39.

Similar to the foregoing display device 10 b, the wavelength conversionsection 40 b also has a constitution in which phosphors 44 a, 44 b and44 c are arranged on the under surface of the transparent substrate 42so as to form a designated pattern. With respect to a material of thephosphors 44 a, 44 b and 44 c, a material exhibiting a light emissioncharacteristics as shown in FIG. 5 should preferably be used. Using suchphosphors, the light in the ultraviolet ray range, which is emitted fromthe light source section 20, can be subjected to the wavelengthconversion with high efficiency. The phosphors 44 a, 44 b and 44 creceives the light in the ultraviolet ray range from the light sourcesection 20 and change the wavelength of the light and emit it, eachbeing in the wavelength ranges of red (R), green (G) and blue (B)colors, respectively.

In the image display device 10 c, the transparent substrate 32 a in thelight adjustment section 30 b is formed of low alkali glass containingalkali elements at a low content ratio. Here, “low alkali glass” meansglass formed of a neutral silicic acid glass having a lower alkalicontent ratio than alkali glass formed of soda lime glass. In the caseof alkali glass, the alkali content ratio is about 13.5% of weight, butin case of low alkali glass, it is about 7% by weight. By using such lowalkali glass, absorption of the ultraviolet ray from the light sourcesection 20 is suppressed so that the display luminance can be increased.

FIG. 7 is a sectional view showing an outline of a concrete structure ofthe image display device 10 d of the present invention. Referring toFIG. 7, the image display device 10 d comprises a light source section20, a light adjustment section 30 c and a wavelength conversion section40 b.

The light source section 20 comprises a semiconductor light emittingelement as a light source, which emits light at the ultraviolet rayrange, similar to the foregoing image display device 10 b. Galliumnitride described above should be used for the material of the lightemitting layer of the semiconductor light emitting element.

The light adjustment section 30 c comprises a structure in which thetransmission ratio of light is adjusted by liquid crystal, similar tothe foregoing image display device 10 b. Specifically in lightadjustment section 30 c, a liquid crystal layer 36 is held betweenpolarization plates 31 and 39.

Similar to the case of the foregoing image display device 10 b, thewavelength conversion section 40 b also has a constitution in which thephosphors 44 a, 44 b and 44 c are arranged on the lower surface of thetransparent substrate 42 so as to form a designated pattern. A materialexhibiting a light emission characteristic as shown in FIG. 5 shouldpreferably be used for the phosphors 44 a, 44 b and 44 c. By using suchphosphors, the light at the ultraviolet ray range, which is emitted fromthe light source section 20, can be subjected to the wavelengthconversion with high efficiency. The phosphors 44 a, 44 b and 44 creceive the light at the ultraviolet ray range from the light sourcesection 20 to change the wavelength of the light and output the lightsat the red (R), green (G) and blue (B) wavelength regions, respectively.

Here, in the image display device 10 d, the transparent substrate 32 bof the light adjustment section 30 c is formed of non-alkali glass whichsubstantially contains no alkali element. Here, “non-alkali glass” meansglass which substantially contains no alkali. By using such non-alkaliglass, the absorption of the ultraviolet ray from the light sourcesection 20 is further suppressed so that the display luminance can beincreased.

FIG. 8 is a sectional view showing an outline of a concrete structure ofthe image display device 10 e of the present invention. Specifically,the image display device 10 e shown in FIG. 8 comprises a light sourcesection 20, a light adjustment section 30 d and a wavelength changesection 40 b.

Similar to the foregoing image display device 10 b, the light sourcesection 20 comprises a semiconductor light emitting element as a lightsource, which emits light in the ultraviolet ray range. For example,gallium nitride which was described above should preferably be used fora material of a light emitting layer of the semiconductor light emittingelement.

Similar to the foregoing image display device 10 b, also the lightadjustment section 30 d also has a constitution in which thetransmission ratio of the light is adjusted by a liquid crystal.Specifically, in the light adjustment section 30 d, a liquid crystallayer 36 is held between polarization plates 31 and 39.

Similar to the foregoing image display device 10 b, the wavelengthconversion section 40 b also has a constitution in which phosphors 44 a,44 b and 44 c are arranged on the lower surface of the transparentsubstrate 42 so as to form a designated pattern. A material exhibitinglight emission characteristic shown in FIG. 5 should preferably be usedfor the phosphors 44 a, 44 b and 44 c. By using such phosphors, thelight from the light source section 20 at the ultraviolet ray range canbe subjected to the wavelength conversion with high efficiency. Thephosphors 44 a, 44 b and 44 c receives the light at the ultraviolet rayrange, emitted from the light source section 20, and change thewavelengths of the light to output the lights in the red (R), green (G)and blue (B) wavelength ranges, respectively.

Here, in the image display device 10 e, the transparent substrate 32 cof the light adjustment section 30 d is formed of quartz glass. Quartzglass has a low alkali content ratio of about 2 ppm, so it exhibits anextremely low absorption ratio for ultraviolet ray. Therefore, theabsorption of the ultraviolet ray is further suppressed, and the displayluminance can be further increased.

FIG. 9 is a sectional view showing an outline of a concrete structure ofthe image display device 10 f of the present invention. Specifically,the image display device 10 f shown in FIG. 9 comprises a light sourcesection 20, a light adjustment section 30 e and a wavelength conversionsection 40 b.

Similar to the foregoing image display device 10 b, the light sourcesection 20 comprises a semiconductor light emitting element as a lightsource, which emits light at the ultraviolet ray range. Gallium nitridewhich was mentioned above should preferably be used for a material ofthe semiconductor light emitting element, for example.

The light adjustment section 30 e also has a constitution in which thetransmission ratio of light is adjusted by a liquid crystal, similar tothe foregoing image display device 10 b. Specifically, the lightadjustment section 30 e has a liquid crystal layer 36 held betweenpolarization plates 31 and 39. Moreover, the transparent substrate 32 dshould be formed of any one of the low alkali glass, non-alkali glass,or quartz glass.

Similar to the foregoing image display device 10 b, the wavelengthchange section 40 b also has a constitution in which phosphors 44 a, 44b and 44 c are arranged on the lower surface of the transparentsubstrate 42 so as to form a designated pattern. A material exhibiting alight emission characteristic as shown in FIG. 5 should be used forphosphors 44 a, 44 b and 44 c. By using such phosphors, the light fromthe light source section 20 in the ultraviolet ray range can besubjected to wavelength conversion with high efficiency. Phosphors 44 a,44 b and 44 c receive the light from the light source section 20 in theultraviolet ray range and change the wavelength of the light, therebyoutputting lights at red (R), green (G) and blue (B) wavelength ranges,respectively.

Here, in image display device 10 f, an ultraviolet ray cutting filter 46is stacked on the wavelength conversion section 40 b. This ultravioletray cutting filter 46 should have a low absorption ratio for visiblelight and a high absorption ratio for ultraviolet ray. By providing suchultraviolet ray cutting filter 46 stacked on the wavelength conversionsection 40 b, the following effects can be obtained.

First, by employing the ultraviolet ray cutting filter 46, the lightemission from the excitation of phosphors 44 a, 44 b and 44 c fromdisturbance light can be suppressed. Specifically, when the ultravioletray is incident from the outside of the image display device 10 f, thephosphors 44 a, 44 b and 44 c are excited, whereby unnecessary lightemission will be produced by them. However, when the ultraviolet raycutting filter 46 is provided, filter 46 absorbs the ultraviolet rayfrom the outside of the image display device 10 f, thereby suppressingthe unnecessary light emission.

Moreover, it is possible to prevent the ultraviolet ray from the lightsource section 20 from leaking to the outside.

When the ultraviolet ray cutting filter 46 is provided between thetransparent substrate 42 of the wavelength conversion section 40 b andthe phosphors 44 a, 44 b and 44 c, the same effects can be obtained.

FIG. 10 is a sectional view showing an outline of the concrete structureof image display device log of the present invention. Specifically, theimage display device log shown in FIG. 10 comprises a light sourcesection 20, a light adjustment section 30 f and a wavelength conversionsection 40 c.

Here, the light source section 20 comprises a semiconductor lightemitting element possessing a peak of light emission in a blue range.For example, a light emitting element employing gallium nitride typesemiconductor can be used.

Similar to the foregoing image display device 10 a, the light adjustmentsection 30 f has a constitution in which the transmission ratio forlight is adjusted by liquid crystal. Specifically, in the lightadjustment section 30 f, the liquid crystal layer 36 is held between thepolarization plates 31 and 39.

The wavelength change section 40 c comprises a phosphor 44 d emittinglight of a red (R) color, a phosphor 44 e emitting light of a green (G)color and a window section 44 f transmitting light of a blue (B) color.Specifically, the phosphor 44 d receives blue colored light which isemitted from the light source section 20 and incident thereto throughthe light adjusting section 30 f. The phosphor 44 d changes itswavelength and outputs it as red color light. Moreover, the phosphor 44e receives the blue color light which is emitted from the light sourcesection 20 and incident through the light adjusting section 30 f. Thephosphor 44 e changes its wavelength and outputs it as green colorlight. Moreover, the window portion 44 f receives the blue color lightwhich is emitted from the light source section 20 and travels throughthe light adjusting section 30 f. The window portion 44 f then transmitsthe received blue color light.

Here, phosphors 44 d and 44 e should be formed of a material exhibitingan absorption excitation peak for the light in a blue color range, thelight being emitted by the light source section 20. In addition, inorder to achieve a high changing efficiency, it should be preferablethat a phosphor formed of an organic material is used. For such organicphosphor, for example, rhodamine B is mentioned for emitting red colorlight, and brilliant sulfoflavine FF is mentioned for emitting greencolor light. On the other hand, the window portion 44 f may beachromatic transparent, or it may be formed of a transparent materialexhibiting a designated absorption ratio in order to balance theluminance of red and blue colors.

Since the image display device log shown in FIG. 10 uses a lightemitting element which emits blue color light as a light source, it hasan advantage that deterioration of material such as the liquid crystallayer can be avoided, the deterioration being produced when ultravioletray is used. Moreover, since the blue color light among the colors to bedisplayed can be outputted without changing its wavelength, loss in thewavelength conversion is small, so that it has an advantage that it iseasy to increase the luminance of an image.

FIG. 11 is a sectional view showing an outline of a concrete example ofthe structure of an image display device 10 h of the present invention.Specifically, the image display device 10 h shown in FIG. 11 comprises alight source section 20, a light adjustment section 30 g and awavelength change section 40 d.

Here, similar to the foregoing image display device 10 b, the lightsource section 20 can use a semiconductor light emitting element whichexhibits a light emission peak in the ultraviolet ray range as a lightsource. Moreover, like the foregoing image display device log, the lightsource section 20 can use a semiconductor light emitting element whichexhibits a light emission peak in the blue color range as a lightsource. Still furthermore, the light source section may use asemiconductor light emitting element which exhibits a light emissionpeak in other wavelength ranges as a light source.

Similar to the foregoing image display device 10 a, the light adjustmentsection 30 g also has a constitution in which a light transmission ratiois adjusted by a liquid crystal. Specifically, also in the lightadjustment section 30 g, a liquid crystal layer 36 is also held betweenpolarization plates 31 and 39.

Similar to the foregoing image display device 10 b, the wavelengthconversion section 40 d can be constituted of phosphors 44 a, 44 b and44 c which are arranged on the lower surface of the transparentsubstrate 42 so as to form a designated pattern, where phosphors 44 a,44 b and 44 c emits lights respectively in red (R), green (G) and blue(B) wavelength ranges. Moreover, in the case where the light sourceemits a blue colored light, the wavelength conversion section 40 d has astructure in which a phosphor 44 d emits a red color (R) light, aphosphor 44 e emits a green color light (G) and a window portion 44 ftransmits a blue color light.

Moreover, in the image display device 10 h, a light diffusion plate 47is provided above the phosphors 44 of the wavelength conversion section40 d. This light diffusion plate 47 diffuses the directions of the lightincident from phosphors 44 and outputs them. By providing such lightdiffusion plate 47, it is possible to widen the visual field angle andsmoothen the image.

FIG. 12 is a sectional view showing an outline of a concrete example ofthe structure of image display device 10 i of the present invention.Specifically, the image display device 10 i in FIG. 12 comprises a lightsource section 20, a light adjustment section 30 g and a wavelengthconversion section 40 e.

Here, in the image display device 10 i, the foregoing light diffusionplate 47 is arranged on the lower layer of phosphors 44. By arrangingsuch light diffusion plate 47, lack of uniformity in luminance of lightsincident onto phosphors 44 can be controlled, allowing each of thephosphors 44 to emit lights uniformly.

Next, an image display device of a second embodiment of the presentinvention will be described.

FIG. 13 is a sectional view showing an outline of a concrete structureof the image display device of the second embodiment of the presentinvention. Specifically, image display device 50 of the presentinvention comprises a light source section 20, a wavelength conversionsection 40 or a wavelength selection section 40 and a light adjustmentsection 30.

In the light source section 20, at least one semiconductor lightemitting element is properly arranged so as to emit light to wavelengthconversion section 40, the light having a designated wavelength, lightamount and luminance distribution. The wavelength conversion section 40changes the wavelength of the light incident from the light sourcesection 20 to output it to the light adjustment section 30. When thewavelength selection section 40 is used, it selects the wavelength ofthe light to output it to the light adjustment section 30.

The light adjustment section 30 adjusts the amount of light incidentfrom either the wavelength conversion section or the wavelengthselection section for each pixel and forms a designated image andoutputs it from the observation plane of the image display device 50.

According to the present invention, since the wavelength conversionsection 40 is provided between the light source section 20 and the lightadjustment section 30, the light from the light source section 20 isnever incident directly onto the light adjustment section 30. Therefore,problems of deterioration and malfunction of the light adjustmentsection 30 due to the direct light from the light source section 20never occurs. Particularly, the liquid crystal layer and the switchingelements in the light adjustment section 30 are prone to deteriorationby the irradiation of ultraviolet ray. However, in the image displaydevice 50, such deterioration never occurs.

In addition, according to the present invention, the light adjustmentsection 30 can be structured so that it has the same structure as thatof the conventional liquid crystal display device. Specifically, thelight incident into the light adjustment section 30 is converted tovisual light, whereby the light adjustment section 30 can be constitutedso as to have the same structure as that of the conventional one.

FIG. 14 is a sectional view showing an outline of a concrete example ofthe structure of the image display device of the present invention.Specifically, the image display device shown in FIG. 50 a comprises alight source section 20, a wavelength conversion section 40 a and alight adjustment section 30 h.

Here, the light source section 20 can use the semiconductor lightemitting element as a light source, which possesses a light emissionpeak in the ultraviolet ray range, like the foregoing image displaydevice 10 b. Moreover, like the foregoing image display device log, itcan use the semiconductor light emitting element as a light source,which possess a light emission peak at the blue color light region.Moreover, it may use a semiconductor light emitting element as a lightsource, which exhibits a light emission peak in other wavelength ranges.

The wavelength conversion section 40 a is provided between the lightsource section 20 and the light adjustment section 30 h. Phosphors 44can be used as its material. It is preferable that the wavelength of anabsorption excitation peak of the phosphors 44 agrees with that of thelight emitting element used in the light source section 20. For example,when the light emitting element formed of gallium nitride as describedabove is used in the light emission section 20, the phosphor exhibitingthe absorption excitation peak as shown in FIG. 5 should be preferablyused for the wavelength conversion section.

As such phosphors, Y₂O₂S:Eu is mentioned for one emitting red coloredlight, (Sr, Ca, Ba, Eu)₁₀(PO₄)₆Cl₂ is mentioned for emitting bluecolored light, and 3(Ba, Mg, Eu, Mn)O.8Al₂O₃ is mentioned for emittinggreen colored light.

Moreover, a second wavelength change section 40 b may be provided underthe light source section, and a reflection plate 68 may be furtherprovided under the second wavelength conversion section 40 b. With suchstructure, the light emitted downward from the light source section 20is subjected to the wavelength conversion, and the light is reflected bythe reflection plate 68. Then, the reflected light travels through thelight source section 20 and the wavelength change section 40 a and isincident onto the light adjustment section 30 h. So it is possible touse the light effectively.

The light adjustment section 30 h has a structure in which a lighttransmission ratio is adjusted by liquid crystal. Specifically, in thelight adjustment section 30 h, a liquid crystal layer 36 is held betweenpolarization plates 31 and 39. The liquid adjustment section 30 h isdesigned so that the molecule orientation state of the liquid crystallayer 36 is controlled by applying a designated voltage between pixelelectrodes 34 and opposite electrodes, and the liquid crystal layer 36controls the light transmission ratio in cooperation with the upper andlower polarization plates 31 and 39. Each of the pixel electrodes 34 issupplied with a designated voltage via the switching element 35. Ametal/insulating film/metal (MIM) junction type device and a thin filmtransistor (TFT) formed of hydrogenized amorphous silicon orpolycrystalline silicon can be used as switching element 35.

FIG. 15 is a sectional view showing an outline of a concrete example ofthe structure of an image display device 50 b which is a modification ofthe image display device 50 a shown in FIG. 14. The image display device50 b shown in FIG. 15 comprises a light source section 20, a wavelengthchange section 40 g and a light adjustment section 30 i.

Here, as has been described concerning the image display device 50 a,the transparent substrate 32 a is provided between the wavelengthconversion section 40 g and the light adjustment section 30 i. The imagedisplay device 50 b has a structure in which an optical property of thetransparent substrate 32 a is changed for each pixel. For example, suchchange of the optical property of the transparent substrate 32 a can beachieved, by providing a range in the substrate 32 a, in which therefraction range is different for each pixel. Or, for each pixel, alight shielding partition may be provided in the substrate 32 a.Moreover, a light shielding pattern may be formed on either bothsurfaces of the substrate 32 a or on one surface thereof.

By changing the optical property of the transparent substrate 32 a foreach pixel, leakage of the light can be prevented when the light travelsfrom the wavelength conversion section 40 g to the light adjustmentsection 30 j through the transparent substrate 32 a. Therefore, pixelblur can be prevented.

FIG. 16 is a sectional view showing an outline of a concrete example ofthe structure of a modification of the image display device of thepresent invention. Specifically, the image display device 50 c shown inFIG. 16 comprises a light source section 20, a wavelength conversionsection 40 h and a light adjustment section 30 j.

However, in the image display device 50 c, the wavelength conversionsection 40 h is disposed between light guiding plate 26 and light source22 of the light source section 20. Specifically, the light from thelight source 22 is subjected to the wavelength conversion by thewavelength conversion section 40 h such that the light has a designatedwavelength, and the light is incident onto the light adjustment section30 j through the light guiding plate 26 thereafter.

The phosphor can be employed as a material of the wavelength conversionsection 40 h, similar to the case of the image display device 50 a. Itshould be preferable that the absorption excitation peak wavelength ofthe phosphor used for this wavelength change section 40 h agrees withthe light emission peak wavelength of the light emitting element used inthe light source 22. For example, when the light emitting element formedof gallium nitride as is described in FIG. 4 is used in the light source22, the phosphor exhibiting the absorption excitation peak shown in FIG.5 should be preferably used for the phosphor of the wavelengthconversion section 40 h.

Moreover, it should be preferable that three kinds of phosphors, whichexhibit light emission peaks in red (R), green (G) and blue (B)wavelength ranges are respectively used in combination with each other.More specifically, the light emission peak wavelengths of the phosphorsshould be selected so as to agree with the transmission spectrumcharacteristic of a color filter 60 of the light adjustment section 30j.

Next, a light adjustment section used suitably for the image displaydevices 10 and 50 of the present invention will be described.

FIG. 17 is a sectional view exemplifying an outline of a structure of atransmission type image display device using a light adjustment device30 k, which can be used in the present invention. In FIG. 17, only thelight source section 20 and the light adjustment section 30 k areillustrated for convenience. A wavelength conversion section (not shown)can be disposed in a similar manner as that in any of the foregoingimage display devices shown in FIGS. 1-3 and 6-16. In FIG. 17, the lightemitted from the light source section 20 is emitted through the lightadjustment section 30 k.

Here, either a guest/host type liquid crystal or high polymer dispersiontype liquid crystal is used as the liquid crystal 36 a of the lightadjustment section 30 k. The guest/host type liquid crystal is one whichtwo color dyes (guest) exhibiting anisotropic properties in absorptionof visible light depending on the long and short axis directions ofmolecules dissolved in a liquid crystal (host) of a constant moleculararrangement. When the guest/host type liquid crystal is used, the lightadjustment section can function with one polarization plate. Therefore,a high light transmission ratio can be obtained and luminance of theimage display device can be increased.

Moreover, the high polymer dispersion type liquid crystal utilizes alight scattering effect of a composite substance composed of nematicliquid crystal and high polymer. The high polymer dispersion type liquidcrystal is roughly divided into NCAP (nematic curvulinear aligned phase)type and PN (polymer network) type. In case of the high polymerdispersion type liquid crystal, a polarization plate is not necessary sothe image display can be achieved with further brightness and a widervisual field angle.

FIG. 18 is a sectional view showing an outline of a concrete example ofthe structure of a reflection type image display device using the lightadjustment section 30 k which has been described above. Specifically, inthe image display device shown in FIG. 18, the light adjustment section30 k is stacked on a reflection plate 28, and further the light sourcesection 20 is stacked on the light adjustment section 20. Then, thelight emitted from the light source section 20 is reflected by thereflection plate 28 through the light adjustment section 30 k, and thenpasses through the light adjustment section 30 k again, and the lightreaches the observer through the light source section 20.

Also in the image display device shown in FIG. 18, the light adjustingsection 30 k uses either a high polymer dispersion type liquid crystalor a guest/host type liquid crystal as liquid crystal 36 a. Therefore,the polarization plate is unnecessary so that the transmission ratio canbe improved. Thus, the image display device of the present invention candisplay a bright image.

FIG. 19 is an explanatory view showing an outline of an example in whicheach area of pixels in the image display device according to the presentinvention is optimized. Specifically, in any of the foregoing imagedisplay devices shown in FIGS. 1 to 18, luminance of each pixel of red(R), green (G) and blue (B) is not necessarily equal to each other. Inorder to adjust the luminance of each pixel, the area of each pixel isset to an appropriate ratio, as shown in FIG. 19, for example.Therefore, each of colors of red (R), green (G) and blue (B) can bedisplayed with an optimized balance, and an image reproducing colorswith neutral tints can be displayed with precision.

Next, a light source section which is suitably used for the imagedisplay device of the present invention will be described. FIGS. 20( a)and 20(b) show an outline of a concrete example of the structure of alight source section 20 of either the image display device 10 or theimage display device 50 of the present invention. Specifically, FIG. 20(a) is a sectional view showing an outline in parallel with theobservation plane of the image display device. FIG. 20( b) is asectional view showing an outline perpendicular to the observation planeof the image display device.

A light source section 20 a illustrated in FIGS. 20( a) and 20(b)comprises a installation section 25 a, to which a light source isinstalled, and a light guiding plate 26. In the installation section 25a, light emitting diode (LED) chips 22 a are arranged as the lightsource. The LED chip 22 a is mounted on, for example, a substrate 24 aand a designated wiring is performed on the chip 22 a. The LED chip 22 ais supplied with a driving electric current, whereby the LED chip 22 ais allowed to emit light. The light which is radiated from the LED chip22 a diverges within the light guiding plate 26, and incident onto alight adjustment section 30 or a wavelength conversion section 40, bothof which are not shown in FIGS. 20( a) and 20(b). Furthermore, since alight extracting efficiency is increased, a reflection plate 28 can bedisposed under the light guiding plate 26, whereby the light emittedfrom the light guiding plate downward can be returned upward. Moreover,in order to reduce the unevenness of luminance of the light, a diffusionplate 29 may be stacked on the light guiding plate 26.

The image display device of the present invention, which uses the lightsource section 20 a, has the following effects in addition to thevarious kinds of the foregoing effects described using FIGS. 1 to 22.

Specifically, since the small sized LED chips 22 a in a so-called barechip state are used, it is possible to make the width W of theinstallation section 25 a small. The installation section 25 a is oftenarranged outside of the display region of the image display device, so aframe section of the image display device, namely, the non-displayregion can be made smaller by narrowing the width W of the installationsection 25 a.

In addition, since the LED chip 22 a in a bare chip state are small, theLED chips 22 a can be densely mounted, whereby luminance of the lightsource can be increased. As a result, a bright and clear image can bedisplayed.

FIGS. 21( a) and 21(b) are structural views showing an outline of thestructure of a second concrete example of the light source of the imagedisplay device according to the present invention. Specifically, FIG.21( a) is a sectional view showing an outline of the light sourcesection in parallel with an observation plane of the image displaydevice, and FIG. 21(b) is a sectional view showing an outline of thelight source section perpendicular to the observation plane thereof.

The light source section 20 b showing in FIGS. 21( a) and 21(b)comprises a installation section 25 b to which a light source isinstalled, and a light guiding plate 26. In the installation section 25b, LED lamps 22 b are arranged. Each LED lamp 22 b has a structure thatan LED chip is mounted on a lead frame, or a stem possessing lead wire,and molded with resin. Each of the LED lamps 22 b can be mounted on thesubstrate 24 b, for example. Moreover, a reflection plate 28 and adiffusion plate 29 may be provided therein (not shown).

The image display device using the light source section 20 b shown inFIGS. 21( a) and 21(b) has the following effects in addition to those ofthe image display device 10 a described above.

Specifically, since the LED lamps 22 b are used, a light collectioncapability by virtue of the lens effect of the mold resin is increased,whereby a light utilization effect can be improved.

Moreover, since the lead wire of the LED lamp 22 b can be inserted intothe substrate 24 b and it can be mounted by only soldering, assemblysteps can be simplified.

FIGS. 22( a) and 22(b) are structural views showing an outline of thestructure of a third concrete example of the light source section of theimage display device according to the present invention. Specifically,FIG. 22( a) is a sectional view showing an outline of the light sourcesection in parallel with an observation plane of the image displaydevice and FIG. 22( b) is a sectional view showing an outline of thelight source section perpendicular to the observation plane thereof.

The light source section 20 c shown in FIGS. 22( a) and 22(b) comprisesa installation section 25 c to which the light source is fitted, and alight guiding plate 26. In the installation section 25 c, surfacemounting (SMD) type lamps 22 c are arranged. Each of the SMD lamps 22 chas a structure that an LED chip is mounted on a small sized mountingsubstrate and it is molded with resin. The SMD lamp 22 c can be mountedon the substrate 24 c, for example. Moreover, a reflection plate 28 anda diffusion plate 29 may be provided therein.

The image display device using the light source section 20 c shown inFIGS. 22( a) and 22(b) has the following effects in addition to theeffects of the foregoing image display device 10 a.

First, since the SMD lamp 22 c is used, assembly steps can besimplified. Specifically, the SMD lamp 22 c can be simply mounted on thesubstrate 24 c according to a so called soldering reflow method,simultaneously when other parts are mounted such as a chip type resistoror a chip type capacitor. In addition, automation of the mounting stepscan easily be realized.

The SMD lamp 22 c is short in height, so that the width W of theinstallation section 25 c of the light source section 20 c can be setsmall. As a result, the size of the frame section of the image displaydevice, that is, the non-display region thereof can be made smaller.

FIGS. 23( a) and 23(b) are structural views showing an outline of thestructure of a fourth concrete example of the light source section ofthe image display device according to the present invention.Specifically, FIG. 23( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device, and FIG. 23( b) is a sectional view showing an outlineof the light source section perpendicular to the observation plane.

The light source section 20 d shown in FIGS. 23( a) and 23(b) comprisesa installation section 25 d to which a light source is installed, and alight guiding plate 26. In the installation section 25 d, LED lamps 22d, 22 e and 22 f exhibiting light emission peaks respectively inwavelength zones of red (R), green (G) and blue (B), are arranged.

As is described above, the LED lamps 22 d, 22 e and 22 f emitting R, Gand B colors are arranged in the installation section 25 d, so that anexisting illumination section of a conventional image display device canbe replaced with them. Specifically, in the conventional liquid crystaldisplay device, a cathode fluorescent tube or an electroluminescenceelement has been used for the illumination section. However, by usingthe light source section 20 d of the present invention, the imagedisplay device of a low power consumption and a long life time can beobtained. In addition, the image display device using the light sourcesection 20 d of the present invention has a high reliability and anability to function with high speed.

FIGS. 24( a) and 24(b) are structural views showing an outline of thestructure of a fifth concrete example of the light source section of theimage display device according to the present invention. Specifically,FIG. 24( a) is a sectional view showing an outline of the light sourcesection in parallel with an observation plane of the image displaydevice, and FIG. 24( b) is a sectional view showing an outline of thelight source section perpendicular to the observation plane thereof.

The light source section 20 e shown in FIGS. 24( a) and 24(b) comprisesSMD lamps 22 g, 22 h and 22 i arranged therein as a light source, whichexhibit light emission peaks in wavelength zones of red (R), green (G)and blue (B) colors, respectively. By using the SMD lamps as describedabove, the light source section 20 e has effects that the width W of theinstallation section 25 e can further be made smaller and the imagedisplay device can be manufactured to be smaller in size, in addition tothe effects of the foregoing light source section 20 d.

Moreover, by using LED chips instead of the SMD lamps 22 g, 22 h and 22i, the width W of the installation section 25 e can be reduced more, sothat the image display device can be made smaller.

FIGS. 25( a) and 25(b) are structural views illustrating an outline ofthe structure of a sixth concrete example of a light source section ofthe image display device according to the present invention.Specifically, FIG. 25( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device, and FIG. 25( b) is a sectional view showing the outlinethereof perpendicular to the observation plane of the image displaydevice.

Similar to the foregoing light source sections 20 d and 20 e, the lightsource section 20 f illustrated in FIGS. 25( a) and 25(b) comprises ainstallation portion 25 f in which semiconductor light emitting elements22 exhibiting light emission peaks in the wavelength zones of forexample, red (R), green (G) and blue (B), respectively, are arranged asa light source.

Then, a light diffusion plate 28 is provided between the installationsection 25 and the light guiding plate 26. By arranging the lightdiffusion plate 28 near the light sources 22, that is, the semiconductorlight emitting elements, the lights of the RGB colors are mixed so thatthe occurrence of unevenness of color can be suppressed.

FIGS. 26( a) and 26(b) are sectional views showing an outline of thestructure of a seventh concrete example of the light source section ofthe image display device according to the present invention.Specifically, FIG. 26( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device and FIG. 26( b) is a sectional view showing the outlinethereof perpendicular to the observation plane.

The light source section 20 g illustrated in FIGS. 26( a) and 26(b)comprises a installation section 25 g arranged on the right and leftends thereof with the light guiding plate 26 interposed therebetween,LED lamps 22 b being arranged in each of 25 g. By arranging the LEDlamps 22 b on both sides of the light guiding plate 26, the number ofthe light sources increases so that luminance of the light sourcesection can be further increased.

FIGS. 27( a) and 27(b) are sectional views showing an outline of thestructure of an eighth concrete example of the light source section ofthe image display device according to the present invention.Specifically, FIG. 27( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device and FIG. 27( b) is a sectional view showing the outlineperpendicular to the observation plane of the image display device.

The light source section 20 h illustrated in FIGS. 27( a) and 27(b)comprises installation sections 25 h arranged in the left and right endportions thereof with the light guiding plate 26 interposedtherebetween, and SMD lamps 22 c being arranged in each of theinstallation sections 25 h and 25 h. By arranging the LED lamps 22 c onboth sides of the light guiding plate 26, the number of the lightsources is increased so that the luminance of the light source sectioncan be increased. Moreover, the width W of the installation section 25 hcan be made smaller compared to the case of the LED lamp 22 c, wherebythe image display device can be made smaller. Furthermore, if the LEDchip 22 a is used instead of the SMD lamp 22 c, the width W of theinstallation section 25 can be reduced more, whereby the size of theimage display device can be made smaller furthermore.

FIG. 28 is a structural view showing an outline of the structure of aninth concrete example of the light source section of the image displaydevice according to the present invention. Specifically, FIG. 28 is asectional view showing an outline of the light source section inparallel with an observation plane of the image display device. Thelight source section 20 i illustrated in FIG. 28 comprises installationsections 25 i arranged at four sides of the light guiding plate 26, andLED lamps 22 b arranged in each of the installation sections 25 i. Byarranging the LED lamps 22 b at the four sides of the light guidingplate 26, the number of the light sources increases so that theluminance of the light source section can be improved furthermore.

FIG. 29 is a structural view showing an outline of the structure of atenth concrete example of the light source section of the image displaysection according to the present invention. Specifically, FIG. 29 is asectional view showing an outline of the light source section inparallel with an observation plane of the image display device. Thelight source section 20 j shown in FIG. 29 comprises installationsections 25 j arranged on four sides of the light guiding plate 26, andSMD lamps 22 c arranged in each of the installation sections 25 j. Byarranging the SMD lamps 22 c on the four sides of the light guidingplate 26, the number of the light sources is further increases so thatthe luminance of the light source section can be further increased.Moreover, the width W of the installation sections 25 j can be reducedin comparison to the case of the LED lamp 22 b, whereby the size of theimage display device can be reduced. Furthermore, if the LED chip 22 ais used instead of the SMD lamp 22 c, the width W of the installationsection 25 can be further reduced so that the size of the image displaydevice can also be further reduced.

FIG. 30 is a structural view showing an outline of the structure of aneleventh concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, FIG. 30is a sectional view showing an outline of the light source section inparallel with an observation plane of the image display device. Thelight source section 20 k shown in FIG. 30 comprises installationsections 25 k arranged on three sides of the light guiding plate 26, anda red colored, green colored and blue colored LED lamps 22 d, 22 e and22 f are respectively arranged in each of the installation sections 25k. By arranging three color LED lamps 22 d, 22 e and 22 f separately onthe three sides of the light guiding plate 26, the occurrence of thelocal color unevenness is suppressed, whereby neutral tinted colors canevenly be obtained on the whole image screen.

FIG. 31 is a constitutional view showing an outline of a twelfthconcrete constitution of the light source section of the image displaydevice according to the present invention. Specifically, FIG. 31 is asectional view showing an outline of the light source section inparallel with the observation plane of the image display device. Thelight source section 201 shown in FIG. 31 comprises installationsections 251 arranged on three sides of the light guiding plate 26, andred color SMD lamps 22 g, green color SMD lamps 22 h and blue color SMDlamps 22 i are arranged in the respective installation sections 251. Byarranging the SMD lamps separately on the three sides of the lightguiding plate 26, the occurrence of the local color unevenness can besuppressed so that neutral tinted colors can be obtained evenly all overthe entire image screen. Moreover, the width W of the installationsection 25 can be reduced more compared to the case of the LED lamp 22b, whereby the side of the image display device can be reduced.Furthermore, if the LED chip 22 a is used instead of the SMD lamp 22 c,the width W of the installation section 25 can be further reduced,whereby the size of the image display device can be further reduced.

FIGS. 32( a) 32(b) are structural views showing an outline of thestructure of a thirteenth concrete example of the light source sectionof the image display device according to the present invention.Specifically, FIG. 32( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device and FIG. 32( b) is a sectional view showing an outline ofthe light source section perpendicular to the observation plane of theimage display device.

The light source section 20 m shown in FIGS. 32( a) and 32(b) comprisesan LED array unit 25 m fitted to one side of the light guiding plate 26.The LED array unit 25 m is a unified part which comprises LED chips 22 aand a rod lens 23 arranged in a designated space between LED array unit25 m and light guiding plate 26. The rod lens 23 has a long cylindricalshape and is arranged along the longitudinal direction of the LED arrayunit 25 m. By using such LED array unit, a light emission intensitydistribution which is uniform in the longitudinal direction of the rodlens can be obtained. The rod lens also converges the light from the LEDchips 22 a in a transverse direction. Moreover, since the light sourcesection 20 m can be constituted only by unifying the light guiding plate26 and the LED array unit, assembly steps can be simplified.

FIG. 33 is a sectional view showing an outline of a fourteenth concreteconstitution of the light source section of the image display deviceaccording to the present invention. Specifically, the image displaydevice shown in FIG. 33 comprises a light source section 20 n and awavelength conversion section 40. Here, the light source section 20 ncomprises a installation section 25 at a one end of its light guidingportion 66, and a movable mirror 70 at the other end thereof. Themovable mirror 70 is designed such that it moves in the arrow directionshown in the drawing and changes its inclination angle. The movablemechanism of the mirror 70 may be moved by a motor or an electromagnet(not shown), or it may use a piezoelectric element. Moreover, themovable mirror 70 may be a slender mirror united in the arrow direction,or may be constituted by arranging individual small mirrors in the arrowdirection, each mirror corresponding to each pixel.

The installation section 25 comprises a light source 22. Here, a lightemitting diode may be used as the light source 22, or a laser diode maybe used. Light emitted from the light source 22 is reflected by themovable mirror 70, and irradiated onto the position of the predetermineddesignated pixel of the wavelength conversion section 40. Therefore, byadjusting the amount of light of the light source 22 and moving themovable mirror 70 in synchronization with the amount of light, light canbe incident onto each pixel of the wavelength change section 40 withdesignated intensity. Thus, a designated image can be displayed.

In a case where a light source such as the light source section 20 n isused, a light adjustment section using liquid crystal will beunnecessary. Therefore, the constitution of the image display device issimplified. Moreover, since it is unnecessary to use liquid crystal, theimage display device can be used in a wide temperature range and theresponse characteristic of the image display is good. The image displaydevice of the present invention can improve its function against weatherconditions.

FIG. 34 is a sectional view showing an outline of the structure of afifteenth concrete constitution of the light source section of the imagedisplay device according to the present invention. Specifically, theimage display device shown in FIG. 34 comprises a light source section20 p and a wavelength conversion section 40. Here, the light sourcesection 20 p comprises a installation section 25 at one end of a lightguiding portion 66. A light emitting diode may be used as the lightsource 22, or a laser diode may be used.

Moreover, the light guiding portion 66 comprises a plurality of movablemirrors 72, 72, . . . , 72 therein, each mirror arranged correspondingto each of the pixel columns. The movable mirrors 72, 72, . . . ,72 aredesigned so that they move in the illustrated arrow direction andreflect the light from the light source section 22 in the correspondingpixels. Each movable mechanism of them may use, for example, a motor oran electromagnet (not shown), or, the movable mechanism may use apiezoelectric element. The movable mirrors 72, 72, . . . , 72 may be aslender mirror unified along the direction of the column of the pixels.Or, each of the movable mirrors 72, 72, . . . , 72 may be arranged as anindividual small mirror, corresponding to each of the pixels in thedirection of corresponding pixel columns.

The light emitted from the light source section 22 is reflected by oneof the movable mirrors 72, 72, . . . , 72, and irradiated onto thecorresponding pixel of the wavelength conversion section 40, the pixelbeing disposed a designated position. Therefore, the amount of light ofthe light source 22 is adjusted and one of the movable mirrors 72, 72, .. . , 72 is moved in synchronization with it. The light is reflected bythe mirror. The light of a designated intensity is allowed to incidentonto each of the pixels of the wavelength conversion section 40. Thus,the designated image can be displayed.

Also in a case where such light source section 20 p is used, the lightadjustment section using liquid crystal is unnecessary. Therefore, theconstitution of the image display device can be simplified. In addition,since it is unnecessary to use liquid crystal, the image display deviceof the present invention can be used in a wide temperature range, andexhibit a good response characteristic for image display. Moreover, theimage display device of the present invention can improve its functionagainst weather conditions.

FIG. 35 is a sectional view showing the outline of the structure of asixteenth concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, theimage display device shown in FIG. 35 comprises a light source section20 q and a wavelength conversion section 40. Here, the light sourcesection 0.20 q comprises a light source 22 at a lowermost end of thelight guiding portion 66. A light emitting diode may be used as thelight source 22, or a laser diode may be used. Moreover, a movable lens74 is arranged in the front of the light source 22. The movable lens 74has an ability to move obliquely and horizontally and to make the lightfrom the light source 22 incident onto a pixel disposed at a designatedposition of the wavelength conversion section 40.

A movable mechanism of the movable lens 74 may use, for example, a motoror an electromagnet (not shown), or the movable mechanism may use apiezoelectric element. Furthermore, a mechanism in which the movablelens 74 is fixed, and the light source 22 is freely movable and thelight from the light source 22 is incident onto the pixel at adesignated position of the wavelength conversion section 40 may beadopted. Also, a combination of the movable lens and a freely movablelight source 22 may be utilized.

The light emitted from the light source 22 is collected by the movablelens 74, and irradiated onto a pixel at a designated position of thewavelength conversion section 40. Therefore, by adjusting the amount oflight from the light source 22, and moving the movable lens 74 insynchronization with it and performing a scan, the light of apredetermined intensity can be incident onto each of the pixels of thewavelength conversion section 40. Thus, a predetermined image can bedisplayed.

In a case where such light source section 20 q is used, a lightadjustment section using liquid crystal is also unnecessary. Therefore,since it is unnecessary to use liquid crystal, the image display deviceof the present invention can be used in a wide temperature range, andexhibit a good response characteristic for image display. The imagedisplay device of the present invention can improve its function againstweather conditions.

FIG. 36 is a sectional view showing an outline of the structure of aseventeenth concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, theimage display device shown in FIG. 36 comprises a light guiding section40, a light adjustment section 30 and a wavelength conversion section40. The light guiding section 66 comprises plural half mirrors 66A eachpixel or for each column therein. The light from the light source isreflected by the half mirror, and reaches the wavelength conversionsection after passing through the light adjustment section 30.

By using the half mirror, light is less scattered compared to the lightsource section using a conventional reflection sheet or dot printingplane. The light from the light source can be conducted to the lightadjustment section effectively since the light is less scattered. Sucheffects will be remarkable when a light source exhibiting a high lightcollection characteristic such as an LED or a semiconductor laser isused. Moreover, if the light source section is designed such that thereflection light passes through the a somewhat smaller area than that ofthe pixel by adjusting the magnitude of the reflection plane of themirror, the leakage of the light between the pixels is suppressed sothat blurring or unsharpness of the pixel can also be prevented.

FIG. 37 is a sectional view showing an outline of the structure of aneighteenth concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, theimage display device illustrated in FIG. 37 comprises a Fresnel typereflection plate 200, which has a reflection surface that transmitsreflection light into each of the pixels. Moreover, a light source 22 ora movable mirror 70 are arranged on the side portion of the lightguiding section 66, whereby the light is sequentially supplied to thecorresponding reflection mirrors.

Alternatively, the light source 22 may be moveable, and light emittedfrom the movable light source is concentrated by the movable lens andscanned in the light guiding section 66, and sequentially irradiated byrespective Fresnel type reflection mirrors onto a pixel at a designatedposition of the wavelength conversion section 40. Whether or not thelight source is moveable, by adjusting the amount of light of the lightsource and moving the movable lens in synchronization with it to performa scan, the light of the predetermined intensity can be supplied to eachof the pixels of the wavelength conversion section. With such structure,the designated image can be displayed.

Also in the case where such light source section is used, a lightadjustment section using liquid crystal or the like is unnecessary.Therefore, the constitution of the image display device of the presentinvention can be simplified. Moreover, since it is unnecessary to useliquid crystal, the image display device can be used in a widetemperature range, and has a good response-characteristic for displayingan image. The image display device of the present invention alsoincreases its resistance to weather conditions.

FIG. 38 is a sectional view showing an outline of the structure of anineteenth concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, in the6 section 66, the image display device illustrated in FIG. 38 alsocomprises a Fresnel type reflection plate 200 having a reflection planewhich emits the reflection light onto each of the pixels.

Moreover, on the side of the light guiding section 30, the movable lightsource 202 is disposed, and the light is sequentially supplied torespective reflection mirrors of the Fresnel type reflection plate 200.Specifically, the movable light source may be designed so that lightemitting elements itself are mechanically moved, such as light emittingelements in an LED and a semiconductor laser, for example.Alternatively, means for polarizing the light may be provided in frontof these light emitting elements (not shown).

The light emitted from the movable light source 202 is scanned in thelight guiding section 66, and sequentially irradiated onto thedesignated pixel location of the wavelength conversion sections by therespective Fresnel type reflection mirrors.

Therefore, by adjusting the amount of light and moving the movable lightsource in synchronization to perform a scan, the light of a designatedintensity can be incident onto the pixels of the wavelength conversionsection 40. Therefore, a designated image can be displayed. In a casewhere such light source sections are used, a light adjustment sectionusing a liquid crystal and the like will be unnecessary. Therefore, theconstitution of the image display device of the present invention can besimplified. Moreover, since it is unnecessary to use a liquid crystal,the image display device of the present invention can be used in a widetemperature range and exhibits a good response characteristic fordisplaying an image. Also resistance to weather conditions can beimproved in the image display device of the present invention.

FIG. 39 is a sectional view showing an outline of the structure of atwentieth concrete example of the light source section of the imagedisplay device according to the present invention. Specifically, in thelight guiding section, the image display device illustrated in FIG. 39also comprises a Fresnel type reflection plate 200 having a reflectionplane which emits the reflection light onto each of the pixels. However,in the image display device illustrated in FIG. 39, a wavelengthconversion section 40 is formed on the reflection plane of the Fresneltype mirror. For example, a phosphor material 204 is deposited in thereflection plane of the mirror as the wavelength conversion section 40.

Moreover, on the side of the light guiding section 66, the movable lightsource 202 is disposed, and the light is sequentially supplied to therespective reflection mirror of the Fresnel type reflection plate 200.Specifically, the movable light source may be designed so that lightemitting elements itself, for example, such as LED and a semiconductorlaser are mechanically moved. Alternatively, means for polarizing thelight may be provided in front of these light emitting elements (notshown).

The light emitted from the movable light source is scanned in the lightguiding section, and sequentially irradiated onto the wavelengthconversion planes which are deposited on the reflection planes of therespective Fresnel type reflection mirrors. Then, the wavelength of thelight is changed so that the light is emitted from observation plane asimage information corresponding to each pixel.

Therefore, by adjusting an amount of light and moving the movable lightsource 202 in synchronization to perform a scan, light of a designatedintensity can be incident onto the respective wavelength conversionsections on the reflection planes which correspond to each pixel. In acase where such light source sections are used, a light adjustmentsection using liquid crystal and the like will be unnecessary. Inaddition, the provision of another wavelength conversion section willalso be unnecessary. Therefore, an extremely simplified constitution ofthe image display device of the present invention can be obtained, andthe image display device of the present invention can be manufactured tobe smaller and thinner. Moreover, since it is unnecessary to use liquidcrystal, the image display device of the present invention can be usedin a wide temperature range and exhibits a good response characteristicfor displaying an image. Also resistance to weather conditions will beimproved in the image display device of the present invention.

FIGS. 40( a) and 40(b) are structural views showing an outline of thestructure of a twenty-first concrete example of the light source sectionof the image display device according to the present invention.Specifically, FIG. 40( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device, and FIG. 40( b) is a sectional view showing the outlineperpendicular to the observation plane of the image display devicethereof.

The light source section 20 r shown in FIGS. 40( a) and 40(b) comprisesa installation section 25 r arranged at one end of the light guidingplate 26. In the installation section 25 r, a laser diodes 22 j as alight source is arranged.

As described above, by using laser diodes 22 j as the light source,light collection characteristics are improved. Moreover, since the imagedisplay device of the present invention can easily narrow down the lightto a form of beam light, the light source section of FIGS. 40( a) and40(b) is especially effective when one or more mirrors of FIGS. 33 and34 perform a light scan.

FIGS. 41( a) and 41(b) are structural view showing an outline of thestructure of a twenty-second concrete example of the light sourcesection of the image display device according to the present invention.Specifically, FIG. 41( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device, and FIG. 41( b) is a sectional view showing an outlinethereof perpendicular to the observation plane of the image displaydevice.

The light source section 20 s illustrated in FIGS. 41( a) and 41(b)comprises LED lamps 22 b arranged on the lower surface of the lightguiding section 26 with designated spaces in between. By illuminatingupward with the LED lamps 22 b, it is possible to significantly reducethe width of the frame section of the image display device, that is, thewidth of the periphery section of the display region, and a reduction insize of the image display device can be realized. Moreover, the LEDlamps 22 b are arranged with a high density, whereby luminance of theimage display device can be easily increased, and thus a bright imagecan be obtained.

FIGS. 42( a) and 42(b) are structural views showing an outline of thestructure of a twenty-third concrete example of the light source sectionof the image display device according to the present invention.Specifically, FIG. 42( a) is a sectional view showing an outline of thelight source section in parallel with an observation plane of the imagedisplay device, and FIG. 42( b) is a sectional view showing an outlineperpendicular to the observation plane of the image display devicethereof.

The light source section 20 t illustrated in FIGS. 42( a) and 42(b)comprises SMD lamps 22 c arranged on the lower surface of the lightguiding section 26 with designated spaces in between. By illuminatingupward with the SMD lamps 22 c, the width of the frame section of theimage display device, that is, the width of the periphery section of thedisplay region can be significantly reduced, whereby the reduction inthe size of the image display device can be realized.

By arranging the SMD lamps 22 c with a high density, luminance can beeasily increased, so that a bright image can be obtained. Moreover,since the SMD lamps 22 c have a smaller dimension in height than that ofthe LED lamps, the thickness of the light source section 20 t can bereduced. By arranging LED chips instead of the SMD lamps 22 c, a higherdensity mounting will be possible thereby further increasing luminance,and, at the same time, the thickness of the light source section 20 tcan further be reduced.

FIG. 43 is a sectional view showing an outline of the structure of atwenty-fourth concrete example of the light source section of the imagedisplay device according to the present invention. The light sourcesection 20 u illustrated in FIG. 43 comprises a substrate 24 u arrangedon the lower surface of the light guiding section 26, and LED lamps 22 barranged on the substrate 24 u with designated spaces in between.Moreover, a reflection plate 76 is provided around each of the LED lamps22 b. By arranging the reflection plates 76 around the corresponding LEDlamps 22 b, it will be possible to extract the light that escapeslaterally or downward and out put it in a direction toward theobservation plane of the image display device, and utilizationefficiency of light is improved.

FIG. 44 is a sectional view showing an outline of the structure of atwenty-fifth concrete example of the light source device of the imagedisplay device according to the present invention. The light sourcesection 20 v illustrated in FIG. 44 comprises a substrate 24 v providedon the lower surface of the light guiding section 26, and SMD lamps 22 carranged on the substrate 24 v with designated spaces in between.Moreover, reflection plates 76 are arranged around each of the SMD lamps22 c. By providing the reflection plates 76, the light that escape fromthe SMD lamps 22 c laterally and downward can be extracted in thefrontward direction of the image display device, thereby improving alight utilization efficiency. Moreover, the same effect can obtained byarranging LED chips instead of the SMD lamps 22 c which includesadvantages due to reduced size.

FIG. 45 is a sectional view showing an outline of the structure of atwenty-sixth concrete example of the light source section of the imagedisplay device according to the present invention. The image displaydevice illustrated in FIG. 45 is a so called projection type imagedisplay device. The image display device illustrated in FIG. 45comprises a light source section 20W, a liquid crystal panel 30 and aprojection lens 80. The light source section 20W comprises a convergentlens 78, a light source 22 and a reflector 77. A light emitting diode isused as the light source 22.

The light irradiated from the light source 22 is reflected by thereflector 77, and converged by the convergent lens 78. Thereafter, theconverged light is incident onto the liquid crystal panel 30. Then, thelight travels through the projection lens 80 so that a designated imageis displayed on screen 90.

By using the light emitting diode as the light source, the life time ofthe light source is prolonged extremely, compared to that of aconventional arc lamp. Moreover, since the rise up time of the lightemitting operation is short, the light source section is capable ofperforming an instantaneous operation.

Next, concrete examples of light sources of the image display deviceaccording to the present invention will be described.

FIG. 46 is a sectional view showing an outline of the structure of afirst concrete example of a light source of the image display deviceaccording to the present invention. The light source 22A shown in FIG.46 comprises a light emitting element 110 and a wavelength conversionmaterial 112 deposited on the surface of the light emitting element 110.Moreover, the electrode portion 114 of the light emitting element 110has a region where the wavelength change material 112 is not deposited.The region is subjected to a wire bonding for making electricalconnections to the light emitting element 110.

The light emitting element 110 is a semiconductor element exhibiting adesignated light emission wavelength peak. Moreover, the light emittingelement 110 may be constituted of a so called a light emitting diode ora semiconductor laser. The material of the light emitting element 110 isproperly determined depending on the required light emission wavelengthzone. For example, in order to emit R, G and B color lights, the lightemitting diode having a light emitting layer formed of gallium nitrideas described in FIG. 4, which emits light of a wavelength in ultravioletray range should be used.

It should be preferable that the wavelength conversion material 112exhibits an absorption excitation peak which agrees with the wavelengthof light emitted from the light emitting element 110. For example, whenthe light emitting element is the one using gallium nitride, it shouldbe preferable that the wavelength conversion material 112 exhibits theabsorption peak as is shown in FIG. 5.

A fluorescent material should be employed as the wavelength changematerial 112. If the wavelength change material 112 is formed of thefluorescent material, any material such as fluorescent dye, fluorescentpigment and fluorescent substance will be sufficient as long as it iscapable of changing the wavelength of the light from the light emittingelement to a different wavelength thereof. Moreover, it is sufficientthat the wavelength conversion material 112 is deposited on at least onepart of the surface of the light emitting element 110.

It is possible to suitably select the wavelength of the light emittedfrom the wavelength change material 112 in accordance with use. Forexample, in order to use the wavelength change material 112 as a lightsource of an image display device performing a full color display, amixture of the fluorescent substances which absorbs emitted ultravioletrays and emits lights having each wavelength of red (R), green (G) andblue (B) color zones, as described referring to FIG. 4. Moreover, whenthe light emitting element 110 emits blue light, a fluorescent substancewhich absorbs this blue light and emits the green and red color lightscan be used. For example, Y₂O₂S:Eu for emitting red color, (Sr, Ca, Ba,Eu)₁₀(PO₄)₆Cl₂ for emitting blue light and 3 (Ba, Mg, Eu, Mn)O.8Al₂O₃can be mentioned for such fluorescent substance.

A light emitting element emits light by recombinations of holes withelectrons inside a semiconductor crystal upon the injection of theelectrons into a semiconductor crystal. In conventional light emittingelements, due to the difference in refraction ratio between thesemiconductor and air or between the semiconductor and mold resin andthe light is partially trapped inside. As a result, the light to beextracted from the light emitting element to the outside was as littleas 2% of the entire light. However, in the light source 22A according tothe present invention, the light reaching the surface of the lightemitting element 110 is absorbed in the wavelength conversion material112 and the wavelength of the light is changed so that the light can beextracted to the outside. The light source 22A shown in FIG. 46 can bemanufactured in the manufacturing steps of the light emitting element110 by depositing the wavelength conversion material 112 on the surfaceof the light emitting element 110 using a sputtering method.Alternatively, the light source 22A can be manufactured either byapplying the wavelength conversion material 112 to the surface of thelight emitting element 110 or coating it thereon, in any of themanufacturing steps for the element 110.

The use of the light source 22A of the present invention is not limitedto a light source of an image display device. Specifically, the lightsource 22A of the present invention can be used as a novel andhigh-performance light source in light sources for various kinds ofdisplay devices such as an indicator or a panel and in light sources forreading and writing of optical disks.

FIG. 47 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, the light source 22A₁ shown in FIG.47 comprises a light emitting element 110, a wavelength conversionmaterial 112 deposited on the surface thereof and a mounting material120. A light emitting diode formed of a gallium nitride type compoundsemiconductor, and a semiconductor laser can be used as the lightemitting element 110, for example. The wavelength conversion material112 is deposited approximately on the entire surface of the lightemitting element 110. A fluorescent substance which absorbs light fromthe light emitting element 110 and emits red (R), green (G) and blue (B)color lights can be used as the wavelength conversion material 112.

The light emitting element 110 is mounted on the bottom surface of a cupsection 121 of the mounting material 120. Moreover, wires 116 and 116are bonded onto the light emitting element 110, and a driving current issupplied via wires 116 to the light emitting element 110.

The light source shown in FIG. 47 is capable of producing the lightshaving a plurality of wavelengths such as red (R), green (G) and blue(B) colors, using one light emitting element. Therefore, theconstitution of the light source is simplified, and the size and weightthereof is reduced. In addition, the driving circuit for the lightsource can also be simplified.

FIG. 48 is a sectional view showing an outline of the structure of aconcrete constitution of the light 22A. Specifically, in the lightsource 22A₂ shown in FIG. 48, the wavelength conversion material 112 isdeposited on the part of the surface of the light emitting element 110.Therefore, the light emitted from the light emitting element 110 ispartially absorbed in the wavelength conversion material 112, and thewavelength of the light is changed. Thereafter, the light is outputtedto the outside. The remaining light is exhausted as light having anintact wavelength as light from the light emitting element 110. Forexample, in a case where the light emitting element 110 produces bluecolor light and the wavelength change material 112 is formed of amaterial which absorbs blue color light and produces red and green colorlights, lights of wavelengths in red (R) color, green (G) color and blue(B) color ranges are obtained.

By adjusting the area where the wavelength conversion material 112 isdeposited, it will be possible to control the intensity balance of therespective wavelength components of lights in the red, green and bluecolor range. For example, when the intensity of the red (R) colorcomponent is increased, it will be sufficient to increase a red (R)color light emission component of the wavelength conversion material112, and at the same time, increase the area for the material.

Specifically, according to the present invention, the lights, having aplurality of wavelengths of the red (R), green (G) and blue (B) colorranges, can be emitted from the light source section. In addition, it ispossible to easily control the intensity balance of the wavelengthcomponents of the red (R), green (G) and blue (B) color lights.

FIG. 49 is a sectional view showing the structure of an outline of aconcrete example of the light source 22A. Specifically, in the lightsource 22A₃ shown in FIG. 49, the wavelength change material 112 isdeposited on the surface of the light emitting element 110, the element110 is mounted on the mounting material 122, and is molded by the resin130. A lead frame or a stem can be used as the mounting material 122.

The foregoing light emitting element using gallium nitride for the lightemitting layer as shown in FIG. 4 can also be used as the light emittingelement. Moreover, the structure of the light emitting element may bethe same as that of a light emitting diode or a semiconductor laser. Thewavelength change material 112 is deposited on at least one part of thesurface of the light emitting element 110. For example, a fluorescentsubstance which absorbs ultraviolet ray from the light emitting element110 and produces lights of wavelengths in red (R), green (G) and blue(B) may be used as a material of the light emitting element. It ispreferable that the absorption excitation peaks of them agrees with thewavelengths of the light emitted from the wavelength of the lightemitting element.

The resin 130 has a light emitting surface formed as a lens. The lightemitted from the light emitting element 110 and the wavelength changematerial 112 deposited on the element 110 can be converged and outputtedby virtue of a lens effect. The light source 22A of the presentinvention has an advantage that the collection efficiency is very highfor the light which has been subjected to the wavelength conversion.

FIG. 50 is a sectional view showing an outline of the conventional lightsource shown for comparison with the present invention. In theconventional light source shown in FIG. 50, the light emitting element210 is mounted on the mounting material 222, and is molded with resin230. Moreover, resin 230 has a light extracting plane formed to belens-like so that resin 230 converges the light from the light emittingelement 210 and outputs it. Moreover, in order to convert the wavelengthof the light emitted from the light emitting element 230 or in order tocompensate a color to the emitted light, a fluorescent substance forconverting the wavelength of the light from the light emitting element210 is mixed into the resin 230. Or, a filter substance 250 forabsorbing range of a designated wavelength of light emitted from theelement 210 is mixed into the resin 230. In many cases, these wavelengthconversion substances 250 are mixed with even distribution into theresin 230.

However, when wavelength conversion substances 250 are mixed into resin230, light will be emitted from each of the wavelength conversionsubstances 250 distributed evenly in the resin 230. Specifically, thearrows shown in the drawing schematically shows the state where afterthe light from the light emitting element collides against thewavelength conversion substance 250, and the wavelength converted lightis scattering. These scattered lights are not converged by the lensbecause the positional relations of the lights with respect to the lensformed on the entire surface of the resin 230 are at random. Therefore,the convergence efficiency is extremely lowered so that luminance isreduced. In addition, when the wavelength change substance 250 isdistributed evenly into the resin 230, a ratio of the lights passingthrough gaps between the wavelength change substances 250 increases sothat the wavelength conversion efficiency is extremely low.

Compared to the conventional light source, in the light source 22A3according to the present invention as shown in FIG. 49, the wavelengthconversion material 112 is deposited on the surface of the lightemitting element 110 so that the light that has been subjected towavelength conversion is effectively converged by the front surface ofthe lens of the resin 130. Moreover, since the wavelength conversionmaterial 112 is deposited directly on the surface of the light emittingelement 110, the wavelength conversion efficiency is extremely high andthe ratio of the lights which are to be subjected to the wavelengthconversion can be easily controlled depending on the area that thewavelength change material 112 is deposited.

According to the present invention, the light emitted from the lightemitting element 110 can be combined with the wavelength conversionmaterial with a high efficiency so the luminance is greatly increased.

For example, when the gallium nitride type light emitting element isused as the light source element 110 and the fluorescent substance whichabsorbs the ultraviolet ray from the light emitting element 110 andproduces the lights having the wavelengths at the red (R), green (G) andblue (B) color range is used as the wavelength change material 112, thelight source emitting a white color of a high luminance can be realized.Such white color light source can be used as a high luminance lightsource, instead of the existing cold cathode fluorescent tube.

FIG. 51 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in the light source 22A₄, the lightsource element 110, the surface of which the wavelength change material112 is deposited on, is mounted on the mounting material 122 such as alead frame and a stem, and the light source element 110 is molded by theresin 130. As the light emitting element, a light emitting element whichuses gallium nitride producing a blue color light as a light emittinglayer can be used. Moreover, the structure of the light emitting elementmay be the same as that of a light emitting diode or a semiconductorlaser.

The wavelength change material 112 is deposited on at least one part ofthe surface of the light emitting element 110. A fluorescent substancewhich absorbs a blue color light from the light emitting element 110 andproduces lights having a wavelength at either a red (R) or green (G)color range, can be used as a substance of the wavelength changematerial 112. An organic fluorescent substance should preferably be usedas such fluorescent substance, from the point of view of its highwavelength conversion efficiency.

The light source 22A, has an ability to simultaneously obtain the bluelight colored light from the light emitting element 110 and the red andgreen colored lights from the wavelength change material 112.Thereafter, the light source 22A, can replace an existing white colorlight source.

FIG. 52 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in FIG. 52, as the light source22A5, an SMD lamp is shown, which comprises the light emitting element110 mounted on the mounting material 122, which the wavelength changematerial 112 is deposited on the surface of the light emitting element110, and the resin 130 molding the light emitting element 110interposing the wavelength change material 112. A substrate or a leadframe can be, for example, used as the mounting member 122.

As the light emitting element 110, the light emitting element usinggallium nitride as a light emitting layer, described in FIG. 4, is used,which emits the light with the wavelength in the ultraviolet ray range.The structure of the element 110 may be the same as those of a lightemitting diode or a semiconductor laser.

The wavelength change material 112 is deposited on at least one part ofthe surface of the light emitting element 110. For a material of thewavelength change material 112, a fluorescent substance which absorbs alight of a wavelength in the ultraviolet ray range and emits lights ofwavelengths of red (R), green (G) and blue (B) color ranges is employed.As such fluorescent substance, the fluorescent substance exhibiting theabsorption characteristic shown in FIG. 5 should be employed, from thepoint of view of its high wavelength conversion efficiency.

A light emitting element emitting a blue colored light is used as thelight emitting element 110. As the wavelength conversion material 112,an organic fluorescent substance may also be used, which absorbs a bluecolor light and emits lights of wavelengths at red (R), blue (B) andgreen (G) color ranges.

The light source 22A₅, is small in size, and is capable of obtaininglights of high luminance at red (R), green (G) and blue (B) colorranges. Therefore, the light source 22A₅ can replace the existing whitecolor light source.

FIG. 53 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in FIG. 53, as the light source22A₆, the LED lamp, the surface of which the wavelength conversionmaterial 112 is deposited on, is shown. This LED lamp has a constitutionthat the light emitting element 110 is mounted on the mounting material122 such as a lead frame and a stem or the element 110 is molded by theresin 130.

As the light emitting element 110, the light emitting element usinggallium nitride as the light emitting layer which emits the ultravioletray light, as described in FIG. 4, is used. Moreover, the structure ofthe element 110 may be the same as those of a light emitting diode or asemiconductor laser.

The wavelength change material 112 is deposited on at least one part ofthe surface of resin 130. A material of the wavelength conversionmaterial 130 is a fluorescent substance which absorbs a ultravioletlight from the light emitting element 110 and emits lights ofwavelengths at red (R), green (G) and blue (B) color regions. As suchfluorescent substance, a fluorescent substance which exhibits theabsorption characteristic shown in FIG. 5 should be employed from thepoint of view of its high wavelength change efficiency.

As the light emitting element 110, a light emitting element emitting ablue colored light is used. As the wavelength change material 112, anorganic fluorescent substance may be also used, which absorbs bluecolored light and emits lights of wavelengths at red (R), blue (B) andgreen (G) color ranges.

The light source 22A₆ can be easily manufactured and is small in size,and is capable of obtaining lights of high luminance at red (R), green(G) and blue (B) color range. Therefore, the light source 22A₆ canreplace the existing white color light source.

FIG. 54 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in FIG. 54, an SMD lamp has asurface on which the wavelength change material 112 is deposited, isshown as the light source 22A₇. This SMD lamp has a constitution thatthe light emitting element 110 is mounted on the mounting material 122such as a substrate and the element 110 is molded by the resin 130.

As the light emitting element 110, the light emitting element usinggallium nitride as the light emitting layer which emits the light of theultraviolet ray, as described in FIG. 4, is used. Moreover, thestructure of the element 110 may be the same as those of a lightemitting diode or a semiconductor laser.

The wavelength conversion material 112 is deposited on at least one partof the surface of the resin 130. A material of the wavelength conversionmaterial 112 is a fluorescent substance which absorbs a ultravioletlight from the light emitting element 110 and emits lights ofwavelengths at red (R), green (G) and blue (B) color regions. As suchfluorescent substance, a fluorescent substance which exhibits theabsorption characteristic shown in FIG. 5 should be employed from thepoint of view of its high wavelength conversion efficiency.

As the light emitting element 110, a light emitting element emitting ablue colored light is used. As the wavelength conversion material 112,an organic fluorescent substance may be also used, which absorbs bluecolored light and emits lights of wavelengths at red (R), blue (B) andgreen (G) color regions.

The light source 22A₇ can be easily be manufacture and is small in size,and is capable of obtaining lights of high luminance at red (R), green(G) and blue (B) color regions. Therefore, the light source 22A₅ canreplace the existing white color light source.

FIG. 55 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in FIG. 55, as the light source22A₈, an LED lamp, in which the wavelength conversion-material 112 isdeposited on the surface of the reflection plate 124 of the lead frame122, is shown. Specifically, this LED lamp has a constitution that thelight emitting element 110 is mounted on the mounting material 122 suchas a substrate and the element 110 is molded by the resin 130.

As the light emitting element 110, the light emitting element usinggallium nitride as the light emitting layer which emits the light of theultraviolet ray, as described in FIG. 4, is used. Moreover, thestructure of the element 110 may be the same as those of a lightemitting diode or a semiconductor laser.

The wavelength conversion material 112 is deposited on at least one partof the surface of reflection plates 124 of the lead frame 122. Amaterial of the wavelength conversion material 112 is a fluorescentsubstance which absorbs ultraviolet light from the light emittingelement 110 and emits lights of wavelengths of red (R), green (G) andblue (B) color range. As such fluorescent substance, a fluorescentsubstance which exhibits the absorption characteristic shown in FIG. 5should be employed from the point of view of its high wavelengthconversion efficiency.

As the light emitting element 110, a light emitting element emitting ablue color light is used. As the wavelength change material 112, anorganic fluorescent substance may be also used, which absorbs a bluecolor light and emits lights of wavelengths of red (R) and green (G)color ranges.

The light source 22A₈ can be easily manufactured and is small in size,and is capable of obtaining lights of high luminance at red (R), green(G) and blue (B) color ranges. Therefore, the light source 22A₈ canreplace the existing white color light source.

FIG. 56 is a sectional view showing an outline of a concrete example ofthe light source 22A. Specifically, in FIG. 56, a light source 22A₉ isshown, in which the wavelength conversion material 112 is deposited onthe light transmission substrate 122 and the light emitting element 110is deposited on the wavelength change material 112. Here, in the lightsource 22A, for example, a designated wire pattern may be formed on thelight transmission substrate 122 and a wire 116 may connect thesubstrate 122 and light emitting element 110.

As the light emitting element 110, the light emitting element usinggallium nitride as the light emitting layer which emits the light of theultraviolet ray, as described in FIG. 4, is used. Moreover, thestructure of the element 110 may be the same as those of a lightemitting diode and a semiconductor laser.

The wavelength conversion material 112 is deposited on at least one partof a facing region between the light emitting element 110 and the lighttransmission substrate 122. A material of the wavelength conversionmaterial is a fluorescent substance which absorbs an ultraviolet raylight from the light emitting element 110 and emits lights ofwavelengths at red (R), green (G) and blue (B) color regions. As suchfluorescent substance, the fluorescent substance exhibiting theabsorption characteristic as shown in FIG. 5 should be used from thepoint of view of its high wavelength-conversion efficiency.

As the light emitting element 110, a light emitting element emitting ablue color light is used. As the wavelength conversion material 112, anorganic fluorescent substance may be also used, which absorbs a bluecolor light and emits lights of wavelengths at red (R) and green (G)color regions. In the light source 22A₉, the light emitted from thelight emitting element 110 is converted to a light of a designatedwavelength in the wavelength conversion material 112, and passes throughthe light transmission substrate 122. Finally, the light is extractedout to the outside.

The light source 22A₉ can also be easily manufactured, and is small insize. Particularly, the thickness of the light source 22A₉ can be madethin. In addition, the light source 22A₉ is capable of obtaining lightsof high luminance at red (R), green (G) and blue (B) color lights.Therefore, the light source 22A₉ can replace the existing white colorlight source.

FIG. 57 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention. The light source 22B shown in FIG. 57 shows a light emittingelement 22B using a gallium nitride type compound semiconductor. Thelight emitting element 22B comprises a semiconductor multilayeredstructure which includes a pn-junction stacked on a substrate 312. Onthe substrate 312, a buffer layer 314, an n-type contact layer 316, ann-type clad layer 318, an activation layer 320, a p-type clad layer 322and a p-type contact layer 324 are formed in this order. The p-typelayers and n-type layers may be stacked on the substrate 312 in areversed order. On the p-type contact layer 324, a transparent electrodelayer 326 is deposited. In addition, on the n-type contact layer 316, ann-type electrode layer 334 is deposited.

When a current is supplied to the light emitting element 22B of suchstructure, a light of a wavelength at a blue color range or anultraviolet range centering around the activation layer 320 can beobtained.

Here, the present invention is characterized in that a wavelengthconversion material is mixed into at least one of the foregoingsubstrate 312, buffer layer 314, n-type contact layer 316, n-type cladlayer 318, activation layer 320, p-type clad layer 322, p-type contactlayer 324 and transparent electrode layer 326. For example, afluorescent substance can be mentioned as such wavelength conversionmaterial.

Such mixing can be realized by adding the wavelength conversion materialinto each of the layers as impurities at the time of crystal growth ofthe layers. Specifically, as an example, the wavelength conversionmaterial can be mixed by vaporizing a fluorescent substance at the timeof crystal growth. Moreover, a phosphor may be injected into thesubstrate 312 in the form of ions.

Phosphors as an insulating film 328 and a protection film 330 may bedeposited by a sputtering method or an electron beam deposition method.Moreover, phosphor films may be deposited between the insulating film328 and the semiconductor layer, or between the protection layer 330 andthe semiconductor layer, using the sputtering method or the electronbeam deposition method. Moreover, the phosphor may be added to theinsulating film 328 and the protection film 330. In addition, thephosphors may be deposited on the surfaces of the insulating film 328and protection film 330.

When the activation layer 320 emits a light of a wavelength at anultraviolet region, the employed phosphors should be the ones whichabsorb an ultraviolet light and emit lights of red (R), green (G) andblue (B) colors, respectively. On the other hand, when the activationlayer 320 emits a light of a wavelength at a blue color region, thephosphors should be the ones which absorb the blue color light and emitred (R) and green (G) color lights, respectively since an organicphosphor particularly exhibits a high wavelength conversion efficiencyfor the blue color light, it should be preferably be used as awavelength change material to be mixed. As such organic phosphor,rhodamine B can be mentioned for the one emitting a red color light, andbrilliantsulfoflavine FF can be mentioned for the one emitting a greencolor.

As described above, by arranging the wavelength conversion material inany position that constitute the semiconductor light emitting element,the wavelength conversion with a high efficiency can be realized in abare chip state.

FIG. 58 is a sectional view showing an outline of the structure of aconcrete example of the light source of the image display device of thepresent invention. In the light source 22C, the light emitting element400 using an indium/gallium/aluminum/phosphor type compoundsemiconductor is mounted on the mounting material 450. The lightemitting element 400 has a semiconductor multilayered structureincluding a pn-junction which is stacked on a gallium arsenic substrate412. On the substrate 412, the buffer layer 414, the n-type clad layer418, the activation layer 420, the p-type clad layer 422 and the p-typecontact layer 424 are formed in this order. Each of the p-type layersand each of the n-type layers may be stacked on the substrate in areverse order. On the p-type contact layer 424, the p-type layer sideelectrode layer 426 is stacked.

When a electric current is supplied to the light emitting element 400with such a structure, light in the green color range centering aroundthe activation layer 420 is emitted from an upper surface of the lightemitting element 400. Moreover, at the same time, a light of awavelength in the red color range is emitted from the side surface ofthe light emitting element 400.

Here, in the present invention, the mounting material 450 comprises areflection plate 460. The light source is designed so that red coloredlight emitted from the side surface of the light emitting element 400 isreflected by the reflection plate 460 upward and the red colored lightis allowed to be extracted together with the green color light. Asdescribed above, the red color light emitted from the side surface ofthe light emitting element 400 is utilized, whereby the light source 22Ccan be used as a red (R) and green (G) light source. Therefore, bycombing the light source 22C with the blue color light emitting element,three lights of red (R), green (G) and blue (B) colors can be obtainedwith the two light emitting elements.

FIG. 59 is a sectional view showing an outline of the structure of aconcrete example of the light source of the image display deviceaccording to the present invention. The light source 22D shown in FIG.59 shows an example in which a small sized light of multi-wavelength isconstituted by stacking light emitting elements emitting lights ofwavelengths different from each other.

Specifically, in the light source 22D shown in FIG. 59, the red colorlight emitting element 510 is stacked over the blue color light emittingelement 500 interposing the connection means 505, and the green colorlight emitting element 520 is stacked over the red color light emittingelement 510 interposing the connection means 515. Here, as theconnection means, metals such as gold and indium can be used forexample. Moreover, the light emitting elements may be connected to eachother by insulating materials, and may be electrically connected bywirings.

When a current is supplied to the light emitting elements stacked onanother, the blue color light from the blue color light emitting element500 can be extracted upward without being shaded by other light emittingelements, as shown by the arrow of FIG. 59. Moreover, from the red colorlight from the red color light emitting element 510, can be transmittedthrough the green color light element 520, and the light can beextracted upward. And the green color light from the green color lightemitting element 520 can be extracted upward without being shaded by thelight emitting elements.

By stacking the light emitting elements emitting the three colors,respectively, the small sized light source with a high luminance can berealized.

FIG. 60 is a sectional view showing an outline of the structure of aconcrete example of the light source of the image display deviceaccording to the present invention. The light source 22E shown in FIG.60 shows another example of a small sized multi-wavelength type lightsource, which is constituted by stacking light emitting elements whichemit lights of wavelengths different from each other.

Specifically, in the light source 22E shown in FIG. 60, the green colorlight emitting element 610 is stacked over the blue color light emittingelement 600 interposing the connection means 605, and the red colorlight emitting element 620 is stacked over the green color lightemitting element 610 interposing the connection means 615. As connectionmeans, metals such as gold and indium can be used, for example.Moreover, the elements may be connected by insulating materials and beelectrically connected by wirings.

Here, in the light source 22E, the light emitting elements are stackedby shifting each of their light emission portions from others so thatthe lights from the light emitting elements can be extracted upwardwithout shading the light from other light emitting elements.

When electric current is supplied to the light emitting elements stackeddescribed above, all of the light from the light emitting elements canbe extracted upward without being shaded, as shown by the arrows in FIG.60.

By stacking the light emitting elements, each emitting one of red (R),green (G) and blue (B) colors, the small sized light source with a highluminance can be realized.

FIG. 61 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention. The light source 22F shown in FIG. 61 shows another exampleof a small sized multi-wavelength type light source which is constitutedby stacking light emitting elements, each emitting a light of awavelength different from each other.

Specifically, in the light source 22F shown in FIG. 61, the green colorlight emitting element 710 is stacked over the red color light emittingelement 700 interposing the connection means 705, and the blue colorlight emitting element 720 is stacked over the green color lightemitting element 710 interposing the connection means 715. As connectionmeans, metals such as gold and indium, for example, can be used.Moreover, the light emitting element may be connected by insulatingmaterials and be electrically connected by wirings (not shown). Whengallium nitride type semiconductor element is used as the blue colorlight emitting element 720, an insulating sapphire is, in many cases,selected as a substrate (not shown). Therefore, when such galliumnitride type semiconductor element is used, the light source 22F shouldbe made by providing a connection hole in the substrate to electricallyconnect the light source element 720 to the light source element 710disposed below, or, alternatively, an electrical wiring should beformed. Moreover, when an element using a silicon carbide type materialis adopted as the blue color light emitting element 720, an electricalconnection between the upper and lower light emitting elements 720 and710 can be secured by the connection means 715 because of an electricalconductivity thereof.

When electric current is supplied to the light emitting elements 700,710 and 720 stacked as described above, the red colored light emittedfrom the red color light emitting element 700 is transmitted through thegreen and blue color emitting elements 710 and 720 as shown by the arrowin FIG. 61, and the light can be extracted upward. This is because thematerials constituting the green and blue color light emitting elements710 and 720 have large band gaps so that the elements 710 and 720possess very small absorption coefficients for the red color light. Fora similar reason, the green colored light emitted from the green colorlight emitting element 710 is transmitted through the blue color lightemitting element 720, whereby the light can be extracted upward.Moreover, the blue colored light emitted from the blue color lightemitting element 720 can be extracted upward without being shaded. Thus,the red (R), green (G) and blue (B) color lights can be extracted at theupper part of the light source 22F.

As described above, by stacking each of the color light emittingelements emitting the red (R), green (G) and blue (B) color lights onanother, a small sized light source with a high luminance can berealized.

FIG. 62 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention. The light source shown in FIG. 62 shows another example incase where a small sized multi-wavelength type light source isconstituted by stacking the red and green color light emitting elementsrespectively on the blue color light emitting element.

Specifically, in the light source shown in FIG. 62, the green colorlight element 710 is stacked on an anode side of the blue color lightemitting element 720, and red color light emitting element 700 isstacked on a cathode electrode side of the blue color light emittingelement 720. The lights emitted from the light emitting elements can beextracted upward as shown in FIG. 62 without interference of the lightsof others.

In such light source, mounting density of the light source elements canbe increased, and mounting can be easily conducted because the elementsneed not be stacked in three layers. Moreover, since an n-up type highluminance red color light emitting diode formed of gallium/aluminumarsenic is mounted on the cathode of the blue color light emittingelement 720, luminance is also greatly improved.

FIG. 63 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to thepresent-invention. The light source shown in FIG. 63 shows anotherexample in a case where a small sized multi-wavelength type light sourceis constituted by stacking the blue color light emitting element 720 onthe green and red color light emitting elements 710 and 700,respectively.

Specifically, in the light source shown in FIG. 63, an anode of the bluecolor light emitting element 720 is stacked on the red color lightemitting element 700, and a cathode of the blue color light emittingelement 720 is stacked on the green color light emitting element 710.The lights emitted from the red and green color light emitting elementsare transmitted through a substrate of the blue color light emittingelement upward and can be extracted.

In the light source constituted as described above, mounting density ofthe elements can be increased, and since the elements need not to bestacked in three layers, mounting of the elements can be easilyconducted. Moreover, since an n-up type high luminance red color lightemitting diode formed of gallium/aluminum arsenic can be used, theluminance can also be improved.

Moreover, since it is not necessary to use a bonding wire, assemblysteps are simplified, resulting in an increase in reliability. Moreover,since the plane for extracting the light is disposed on the substrateside of the blue color light emitting element, the efficiency for lightextracting of the blue color light emitting element is increased. Sincethe lights emitted from the red and green light emitting elements havingcomparatively small band gap are transmitted through the blue colorlight emitting element having a large band gap, the lights can beeffectively extracted without being absorbed.

FIG. 64 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention specifically, in FIG. 64, the LED lamp in which a plurality oflight emitting elements are mounted is shown as the light source 22G.Specifically, the LED lamp has a constitution that the light emittingelements 810 a, 810 b, . . . , 810 d emitting lights of wavelengths inred (R), green (G) and blue (B) color ranges are mounted on the mountingmaterial 820 and molded by resin 830.

Specifically, in the example illustrated in FIG. 64, the LED lamps isshown, in which the red color light emitting element 810 a, the bluecolor light emitting element 810 b and the green color light emittingelement 810 c and 810 d are mounted on the lead frame 820.

As described above, by installing the light emitting elements, each ofwhich emits different colored light, in one package, the small sizedlight source with high luminance and reliability can be realized.

Moreover, the acquisition of the red (R), green (G) and blue (B) colorlights with high luminance by the light source 22G replaces an existingwhite color light source.

FIG. 65 is a sectional view showing an outline of a concrete example ofthe light source of the image display device according to the presentinvention. Specifically, in FIG. 65, an SMD lamp, in which a pluralityof light emitting elements are mounted, is shown as the light source22H. The SMD lamp has a constitution that the light emitting elements910 a, 910 b . . . each emitting one of the red (R), green (G) and blue(B) color lights, are mounted on the mounting material 920 and molded byresin 930.

In the example shown in FIG. 65, the SMD lamp is shown, in which the redcolor light emitting element 910 a, the blue color light emittingelement 910 b and the green color light emitting element 910 c and 910 d(not shown) are mounted on the mounting material 920.

As described above, by installing the light emitting elements, each ofwhich emits one of the red (R), green (G) and blue (B) color lights, inone package, the small sized light source with high luminance andreliability can be realized.

Moreover, the acquisition of the red (R), green (G) and blue (B) colorlights with high luminance by the light source 22H replaces an existingwhite color light source.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A semiconductor light emitting device, comprising: a mounting memberhaving a main surface; a light emitting element mounted on the mainsurface of the mounting member; and a wavelength change materialprovided on a surface of the light emitting element with covering anexposed surface of the light emitting element.